2024-03-28T13:55:52Zhttp://uvadoc.uva.es/oai/requestoai:uvadoc.uva.es:10324/280122021-06-24T07:18:58Zcom_10324_1148com_10324_931com_10324_894com_10324_28025com_10324_954col_10324_1270col_10324_28026
Pelaz Montes, María Lourdes
Marqués Cuesta, Luis Alberto
Aboy Cebrián, María
López Martín, Pedro
Santos Tejido, Iván
2018-01-11T08:06:51Z
2018-01-11T08:06:51Z
2017
Materials Science in Semiconductor Processing Volume 62, 2017, Pages 62-79
http://uvadoc.uva.es/handle/10324/28012
https://doi.org/10.1016/j.mssp.2016.11.007
We review atomistic modeling approaches for issues related to ion implantation and annealing in advanced device processing. We describe how models have been upgraded to capture physical mechanisms in more detail as a response to the accuracy demanded in modern process and device modeling. Implantation and damage models based on the binary collision approximation have been improved to describe the direct formation of amorphous pockets for heavy or molecular ions. The use of amorphizing implants followed by solid phase epitaxial regrowth has motivated the development of detailed models that account for amorphization and recrystallization, considering the influence of crystal orientation and stress conditions. We apply simulations to describe the role of implant parameters to minimize residual damage, and we address doping issues that arise in non-planar structures such as FinFETs.
eng
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Attribution-NonCommercial-NoDerivatives 4.0 International
Improved physical models for advanced silicon device processing
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/280132021-06-24T07:18:59Zcom_10324_1148com_10324_931com_10324_894com_10324_28025com_10324_954col_10324_1270col_10324_28026
Santos Tejido, Iván
Aboy Cebrián, María
López Martín, Pedro
Marqués Cuesta, Luis Alberto
Pelaz Montes, María Lourdes
2018-01-11T08:33:34Z
2018-01-11T08:33:34Z
2016
Journal of Physics D: Applied Physics, Volume 49, Number 7, 2016
http://uvadoc.uva.es/handle/10324/28013
https://doi.org/10.1088/0022-3727/49/7/075109
We have used atomistic simulations to identify and characterize interstitial defect cluster configurations candidate for W and X photoluminescence centers in crystalline Si. The configurational landscape of small self-interstitial defect clusters has been explored through nanosecond annealing and implantation recoil simulations using classical molecular dynamics. Among the large collection of defect configurations obtained, we have selected those defects with the trigonal symmetry of the W center, and the tetrahedral and tetragonal symmetry of the X center. These defect configurations have been characterized using ab initio simulations in terms of their donor levels, their local vibrational modes, the defect induced modifications of the electronic band structure, and the transition amplitudes at band edges. We have found that the so-called I3-V is the most likely candidate for the W PL center. It has a donor level and local vibrational modes in better agreement with experiments, a lower formation energy, and stronger transition amplitudes than the so-called I3-I, which was previously proposed as the W center. With respect to defect candidates for the X PL center, our calculations have shown that none of the analyzed defect candidates match all of the experimental characteristics of the X center. Although the Arai tetra-interstitial configuration previously proposed as the X center cannot be excluded, the other defect candidates for the X center found, I3-C and I3-X, cannot be discarded either.
eng
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Attribution-NonCommercial-NoDerivatives 4.0 International
Insights on the atomistic origin of X and W photoluminescence lines in c-Si from ab initio simulations
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/280142021-06-24T07:18:57Zcom_10324_1148com_10324_931com_10324_894com_10324_28025com_10324_954col_10324_1270col_10324_28026
Marqués Cuesta, Luis Alberto
Santos Tejido, Iván
Pelaz Montes, María Lourdes
López Martín, Pedro
Aboy Cebrián, María
2018-01-11T08:50:31Z
2018-01-11T08:50:31Z
2016
Materials Science in Semiconductor Processing Volume 42, Part 2, 2016, Pages 235-238
http://uvadoc.uva.es/handle/10324/28014
https://doi.org/10.1016/j.mssp.2015.07.020
We have studied the early stages of self-interstitial clustering in silicon using molecular dynamics simulation techniques. We have generated silicon samples of over 200,000 atoms where we introduced a 0.5% extra concentration of self-interstitials. Then samples were annealed at several temperatures. During the simulations we observed the formation of interstitial clusters with different atomic structures, ranging from spherical and amorphous-like clusters, to highly ordered extended configurations such as (110) chains, {111} rod-like defects and dislocation loops, and {100} planar defects. This last type of defects, while common in germanium, have not been observed in silicon until very recently, in ultra-fast laser annealing experiments. The particular morphology of formed interstitial clusters is found to be related to the annealing temperature, as it is observed in the experiments. From the molecular dynamics simulations we have analyzed the atomic mechanisms leading to the formation and growth of interstitial clusters, with special attention to the newly found {100} planar defects
eng
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Attribution-NonCommercial-NoDerivatives 4.0 International
Molecular dynamics simulation of the early stages of self-interstitial clustering in silicon
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/280152021-06-24T07:18:37Zcom_10324_1148com_10324_931com_10324_894com_10324_28025com_10324_954col_10324_1270col_10324_28026
Marqués Cuesta, Luis Alberto
Santos Tejido, Iván
Pelaz Montes, María Lourdes
López Martín, Pedro
Aboy Cebrián, María
2018-01-11T09:10:22Z
2018-01-11T09:10:22Z
2015
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 352, 2015, Pages 148-151
http://uvadoc.uva.es/handle/10324/28015
https://doi.org/10.1016/j.nimb.2014.11.105
Requirements for the manufacturing of electronic devices at the nanometric scale are becoming more and more demanding on each new technology node, driving the need for the fabrication of ultra-shallow junctions and finFET structures. Main implantation strategies, cluster and cold implants, are aimed to reduce the amount of end-of-range defects through substrate amorphization. During finFET doping the device body gets amorphized, and its regrowth is more problematic than in the case of conventional planar devices. Consequently, there is a renewed interest on the modeling of amorphization and recrystallization in the front-end processing of Si. We present multi-scale simulation schemes to model amorphization and recrystallization in Si from an atomistic perspective. Models are able to correctly predict damage formation, accumulation and regrowth, both in the ballistic and thermal-spike regimes, in very good agreement with conventional molecular dynamics techniques but at a much lower computational cost.
eng
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http://creativecommons.org/licenses/by-nc-nd/4.0/
Attribution-NonCommercial-NoDerivatives 4.0 International
Atomistic modeling of ion implantation technologies in silicon
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/280162021-06-24T07:19:00Zcom_10324_1148com_10324_931com_10324_894com_10324_28025com_10324_954col_10324_1270col_10324_28026
López Martín, Pedro
Santos Tejido, Iván
Aboy Cebrián, María
Marqués Cuesta, Luis Alberto
Pelaz Montes, María Lourdes
2018-01-11T09:37:31Z
2018-01-11T09:37:31Z
2015
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 352, 2015, Pages 156-159
http://uvadoc.uva.es/handle/10324/28016
https://doi.org/10.1016/j.nimb.2014.12.026
New criteria are presented for the classification and statistical analysis of defects from irradiation cascades that allow a more detailed description of the diversity of damage, especially amorphous regions. Classical molecular dynamics simulations are used to analyze the damage produced by 2 keV Si recoils annealed at 1000 K for 1 ns. Based on a density grouping criterion of elementary defects (displaced atoms and empty lattice sites) the non-uniformity of local defect density within damage regions is revealed. The density criterion is able to distinguish dense damage regions which evolve independently upon annealing (although they are connected by some defects), while keeping small and compact regions unaltered. Damage regions are classified according to the size, net number of defects and compactness, calculated by averaging the distance among all defects, parameters that have a direct impact on their stability.
eng
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Attribution-NonCommercial-NoDerivatives 4.0 International
A detailed approach for the classification and statistical analysis of irradiation induced defects
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/280702021-06-24T07:18:53Zcom_10324_1148com_10324_931com_10324_894com_10324_28025com_10324_954col_10324_1270col_10324_28026
Marqués Cuesta, Luis Alberto
Aboy Cebrián, María
Santos Tejido, Iván
López Martín, Pedro
Cristiano, Fuccio
La Magna, Antonino
Huet, Karim
Tabata, Toshiyuki
Pelaz Montes, María Lourdes
2018-01-16T11:36:07Z
2018-01-16T11:36:07Z
2017
Physical Review Letters Vol. 119, Iss. 20, 2017
0031-9007
http://uvadoc.uva.es/handle/10324/28070
https://doi.org/10.1103/PhysRevLett.119.205503
Ultra-fast laser annealing of ion implanted Si has led to thermodynamically unexpected large {001} self-interstitial loops, and the failure of Ostwald ripening models for describing self-interstitial cluster growth. We have carried out molecular dynamics simulations in combination with focused experiments in order to demonstrate that at temperatures close to the melting point, self-interstitial rich Si is driven into dense liquid-like droplets that are highly mobile within the solid crystalline Si matrix. These liquid droplets grow by a coalescence mechanism and eventually transform into {001} loops through a liquid-to-solid phase transition in the nanosecond timescale.
eng
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http://creativecommons.org/licenses/by-nc-nd/4.0/
Attribution-NonCommercial-NoDerivatives 4.0 International
Ultrafast generation of unconventional {001} loops in Si
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/286162021-06-24T07:18:50Zcom_10324_1148com_10324_931com_10324_894com_10324_28025com_10324_954col_10324_1270col_10324_28026
Marqués Cuesta, Luis Alberto
Aboy Cebrián, María
Dudeck, Karleen J.
Botton, Gianluigi A.
Knights, Andrew P.
Gwilliam, Russell M.
2018-02-20T11:40:01Z
2018-02-20T11:40:01Z
2014
Journal of Applied Physics, 2014, 115, p. 143514
0021-8979
http://uvadoc.uva.es/handle/10324/28616
https://doi.org/10.1063/1.4871538
We propose an atomistic model to describe extended {311} defects in silicon. It is based on the combination of interstitial and bond defect chains. The model is able to accurately reproduce not only planar {311} defects but also defect structures that show steps, bends, or both. We use molecular dynamics techniques to show that these interstitial and bond defect chains spontaneously transform into extended {311} defects. Simulations are validated by comparing with precise experimental measurements on actual {311} defects. The excellent agreement between the simulated and experimentally derived structures, regarding individual atomic positions and shape of the distinct structural {311} defect units, provides strong evidence for the robustness of the proposed model.
eng
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http://creativecommons.org/licenses/by-nc-nd/4.0/
Attribution-NonCommercial-NoDerivatives 4.0 International
Modeling and experimental characterization of stepped and v-shaped {311} defects in silicon
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/286192021-06-24T07:19:04Zcom_10324_1148com_10324_931com_10324_894com_10324_28025com_10324_954col_10324_1270col_10324_28026
Santos Tejido, Iván
Cazzaniga, Marco
Onida, Giovanni
Colombo, Luciano
2018-02-20T11:58:20Z
2018-02-20T11:58:20Z
2014
Journal of Physics: Condensed Matter, 2014, Volume 26, Number 9
0953-8984
http://uvadoc.uva.es/handle/10324/28619
http://dx.doi.org/10.1088/0953-8984/26/9/095001
We investigate the structural and electronic properties of the interface between hydrogenated amorphous silicon (a-Si:H) and crystalline silicon (c-Si) by combining tight-binding molecular dynamics and DFT ab initio electronic structure calculations. We focus on the c-Si(100)(1×1)/a-Si:H, c-Si(100)(2×1)/a-Si:H and c-Si(111)/a-Si:H interfaces, due to their technological relevance. The analysis of atomic rearrangements induced at the interface by the interaction between H and Si allowed us to identify the relevant steps that lead to the transformation from c-Si(100)(1×1)/a-Si:H to c-Si(100)(2×1)/a-Si:H. The interface electronic structure is found to be characterized by spatially localized mid-gap states. Through them we have identified the relevant atomic structures responsible for the interface defect states, namely: dangling-bonds, H bridges, and strained bonds. Our analysis contributes to a better understanding of the role of such defects in c-Si/a-Si:H interfaces.
eng
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
Attribution-NonCommercial-NoDerivatives 4.0 International
Atomistic study of the structural and electronic properties of a-Si:H/c-Si interfaces
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/286202021-06-24T07:18:48Zcom_10324_1148com_10324_931com_10324_894com_10324_28025com_10324_954col_10324_1270col_10324_28026
Aboy Cebrián, María
Santos Tejido, Iván
Pelaz Montes, María Lourdes
Marqués Cuesta, Luis Alberto
López Martín, Pedro
2018-02-20T12:11:54Z
2018-02-20T12:11:54Z
2014
Journal of Computational Electronics, 2014, Volume 13, Issue 1, pp 40–58
1569-8025
http://uvadoc.uva.es/handle/10324/28620
10.1007/s10825-013-0512-5
Ion implantation is a very well established technique to introduce dopants in semiconductors. This technique has been traditionally used for junction formation in integrated circuit processing, and recently also in solar cells fabrication. In any case, ion implantation causes damage in the silicon lattice that has adverse effects on the performance of devices and the efficiency of solar cells. Alternatively, damage may also have beneficial applications as some studies suggest that small defects may be optically active. Therefore it is important an accurate characterization of defect structures formed upon irradiation. Furthermore, the technological evolution of electronic devices towards the nanometer scale has driven the need for the formation of ultra-shallow and low-resistive junctions. Ion implantation and thermal anneal models are required to predict dopants placement and electrical activation. In this article, we review the main models involved in process simulation, including ion implantation, evolution of point and extended defects and dopant-defect interactions. We identify different regimes at which each type of defect is more relevant and its inclusion in the models becomes crucial. We illustrate in some examples the use of atomistic modeling techniques to gain insight into the physics involved in the processes as well as the relevance of the accuracy of models.
eng
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http://creativecommons.org/licenses/by-nc-nd/4.0/
Attribution-NonCommercial-NoDerivatives 4.0 International
Modeling of defects, dopant diffusion and clustering in silicon
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/286222021-06-22T07:28:25Zcom_10324_1148com_10324_931com_10324_894com_10324_28025com_10324_954col_10324_1270col_10324_28026
Fisicaro, Giuseppe
Pelaz Montes, María Lourdes
Aboy Cebrián, María
López Martín, Pedro
Italia, Markus
Huet, Karim
Cristiano, Filadelfo
Essa, Zahi
Yang, Qui
Bedel Pereira, Elena
Quillec, Maurice
La Magna, Antonino
2018-02-20T12:34:57Z
2018-02-20T12:34:57Z
2014
Applied Physics Express, 2014, Volume 7, Number 2
1882-0778
http://uvadoc.uva.es/handle/10324/28622
http://dx.doi.org/10.7567/APEX.7.021301
We investigate the correlation between dopant activation and damage evolution in boron-implanted silicon under excimer laser irradiation. The dopant activation efficiency in the solid phase was measured under a wide range of irradiation conditions and simulated using coupled phase-field and kinetic Monte Carlo models. With the inclusion of dopant atoms, the presented code extends the capabilities of a previous version, allowing its definitive validation by means of detailed comparisons with experimental data. The stochastic method predicts the post-implant kinetics of the defect-dopant system in the far-from-equilibrium conditions caused by laser irradiation. The simulations explain the dopant activation dynamics and demonstrate that the competitive dopant-defect kinetics during the first laser annealing treatment dominates the activation phenomenon, stabilizing the system against additional laser irradiation steps.
eng
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
Attribution-NonCommercial-NoDerivatives 4.0 International
Kinetic Monte Carlo simulations of boron activation in implanted Si under laser thermal annealing
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/289632021-06-24T07:19:02Zcom_10324_1148com_10324_931com_10324_894com_10324_28025com_10324_954col_10324_1270col_10324_28026
Dudeck, Karleen J.
Marqués Cuesta, Luis Alberto
Knights, Andrew P.
Gwilliam, Russell M.
Botton, Gianluigi A.
2018-03-13T09:02:44Z
2018-03-13T09:02:44Z
2013
Physical Review Letters, 2013, Vol. 110, 166102
0031-9007
http://uvadoc.uva.es/handle/10324/28963
https://doi.org/10.1103/PhysRevLett.110.166102
n this Letter we present the detailed, quantitative comparison between experimentally and theoretically derived structures of the extended {311} defect in silicon. Agreement between experimental and theoretical column positions of better than ±0.05 nm has been achieved for all 100 atomic columns in the defect structure. This represents a calculated density of 5.5×1014 silicon interstitials per cm2 on {311} planes, in agreement with previous work [S. Takeda, Jpn. J. Appl. Phys., Part 2, 30, L639 (1991)]. We show that although the {311} defect is made up of five-, six-, seven-, and eight-member rings, the shape of these rings varies as a function of position along the defect, and these variations can be determined experimentally with high precision and accuracy. The excellent agreement between the calculated and experimentally derived structure, including the position of atomic columns and the shape of the distinct structural units of the defect, provides strong evidence for the quality and robustness of the molecular dynamics simulation approach for structural studies of defects. The experimental approach is straightforward, without the need for complicated image processing methods, and is therefore widely applicable.
eng
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http://creativecommons.org/licenses/by-nc-nd/4.0/
Attribution-NonCommercial-NoDerivatives 4.0 International
Sub-ångstrom Experimental Validation of Molecular Dynamics for Predictive Modeling of Extended Defect Structures in Si
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/289652021-06-24T07:18:40Zcom_10324_1148com_10324_931com_10324_894com_10324_28025com_10324_954col_10324_1270col_10324_28026
Marqués Cuesta, Luis Alberto
Pelaz Montes, María Lourdes
Santos Tejido, Iván
López Martín, Pedro
Duffy, Ray
2018-03-13T09:47:31Z
2018-03-13T09:47:31Z
2012
Journal of Applied Physics, 2012, 111, 034302
http://uvadoc.uva.es/handle/10324/28965
https://doi.org/10.1063/1.3679126
We use molecular dynamics (MD) simulation techniques to study the regrowth of nanometric multigate Si devices, such as fins and nanowires, surrounded by free surfaces and interfaces with amorphous material. Our results indicate that atoms in amorphous regions close to lateral free surfaces or interfaces rearrange at a slower rate compared to those in bulk due to the discontinuity of the lateral crystalline template. Consequently, the recrystallization front which advances faster in the device center than at the interfaces adopts new orientations. Regrowth then proceeds depending on the particular orientation of the new amorphous/crystal interfaces. In the particular case of 〈110〉 oriented fins, the new amorphous/crystal interfaces are aligned along the 〈111〉 direction, which produces frequent twining during further regrowth. Based on our simulation results, we propose alternatives to overcome this defected recrystallization in multigate structures: device orientation along 〈100〉 to prevent the formation of limiting {111} amorphous/crystal interfaces and presence of a crystalline seed along the device body to favor regrowth perpendicular to the lateral surfaces/interfaces rather than parallel to them.
eng
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http://creativecommons.org/licenses/by-nc-nd/4.0/
© American Institute of Physics
Attribution-NonCommercial-NoDerivatives 4.0 International
Molecular dynamics simulation of the regrowth of nanometric multigate Si devices
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/289702021-06-24T07:18:35Zcom_10324_1148com_10324_931com_10324_894com_10324_28025com_10324_954col_10324_1270col_10324_28026
López Martín, Pedro
Pelaz Montes, María Lourdes
Santos Tejido, Iván
Marqués Cuesta, Luis Alberto
Aboy Cebrián, María
2018-03-13T11:23:52Z
2018-03-13T11:23:52Z
2012
Journal of Applied Physics, 2012, 111, 033519
http://uvadoc.uva.es/handle/10324/28970
https://doi.org/10.1063/1.3682108
Molecular dynamics simulation techniques are used to analyze damage production in Ge by the thermal spike process and to compare the results to those obtained for Si. As simulation results are sensitive to the choice of the inter-atomic potential, several potentials are compared in terms of material properties relevant for damage generation, and the most suitable potentials for this kind of analysis are identified. A simplified simulation scheme is used to characterize, in a controlled way, the damage generation through the local melting of regions in which energy is deposited. Our results show the outstanding role of thermal spikes in Ge, since the lower melting temperature and thermal conductivity of Ge make this process much more efficient in terms of damage generation than in Si. The study is extended to the modeling of full implant cascades, in which both collision events and thermal spikes coexist. Our simulations reveal the existence of bigger damaged or amorphous regions in Ge than in Si, which may be formed by the melting and successive quenching induced by thermal spikes. In the particular case of heavy ion implantation, defect structures in Ge are not only bigger, but they also present a larger net content in vacancies than in Si, which may act as precursors for the growth of voids and the subsequent formation of honeycomb-like structures.
eng
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http://creativecommons.org/licenses/by-nc-nd/4.0/
© American Institute of Physics
Attribution-NonCommercial-NoDerivatives 4.0 International
Molecular dynamics simulations of damage production by thermal spikes in Ge
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/289692021-06-24T07:18:36Zcom_10324_1148com_10324_931com_10324_894com_10324_28025com_10324_954col_10324_1270col_10324_28026
Fisicaro, Giuseppe
Pelaz Montes, María Lourdes
López Martín, Pedro
La Magna, Antonino
2018-03-13T11:15:49Z
2018-03-13T11:15:49Z
2012
Physical Review E, 2012, 86, 036705
1539-3755
http://uvadoc.uva.es/handle/10324/28969
https://doi.org/10.1103/PhysRevE.86.036705
Pulsed laser irradiation of damaged solids promotes ultrafast nonequilibrium kinetics, on the submicrosecond scale, leading to microscopic modifications of the material state. Reliable theoretical predictions of this evolution can be achieved only by simulating particle interactions in the presence of large and transient gradients of the thermal field. We propose a kinetic Monte Carlo (KMC) method for the simulation of damaged systems in the extremely far-from-equilibrium conditions caused by the laser irradiation. The reference systems are nonideal crystals containing point defect excesses, an order of magnitude larger than the equilibrium density, due to a preirradiation ion implantation process. The thermal and, eventual, melting problem is solved within the phase-field methodology, and the numerical solutions for the space- and time-dependent thermal field were then dynamically coupled to the KMC code. The formalism, implementation, and related tests of our computational code are discussed in detail. As an application example we analyze the evolution of the defect system caused by P ion implantation in Si under nanosecond pulsed irradiation. The simulation results suggest a significant annihilation of the implantation damage which can be well controlled by the laser fluence.
eng
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http://creativecommons.org/licenses/by-nc-nd/4.0/
© American Physical Society
Attribution-NonCommercial-NoDerivatives 4.0 International
Kinetic Monte Carlo simulations for transient thermal fields: Computational methodology and application to the submicrosecond laser processes in implanted silicon
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/309812021-06-24T07:18:54Zcom_10324_28025com_10324_954com_10324_894com_10324_1148com_10324_931col_10324_28026col_10324_1270
Aboy Cebrián, María
Santos Tejido, Iván
López Martín, Pedro
Marqués Cuesta, Luis Alberto
Pelaz Montes, María Lourdes
2018-07-27T07:59:30Z
2018-07-27T07:59:30Z
2018
Journal of Electronic Materials, 2018, Volume 47, Issue 9, pp 5045–5049
0361-5235
http://uvadoc.uva.es/handle/10324/30981
https://doi.org/10.1007/s11664-018-6300-z
Several atomistic techniques have been combined to identify the structure of defects responsible for X and W photoluminescence lines in crystalline Si. We used kinetic Monte Carlo simulations to reproduce irradiation and annealing conditions used in photoluminescence experiments. We found that W and X radiative centers are related to small Si self-interstitial clusters but coexist with larger Si self-interstitials clusters that can act as nonradiative centers. We used molecular dynamics simulations to explore the many different configurations of small Si self-interstitial clusters, and selected those having symmetry compatible with W and X photoluminescence centers. Using ab initio simulations, we calculated their formation energy, donor levels, and energy of local vibrational modes. On the basis of photoluminescence experiments and our multiscale theoretical calculations, we discuss the possible atomic configurations responsible for W and X photoluminescence centers in Si. Our simulations also reveal that the intensity of photoluminescence lines is the result of competition between radiative centers and nonradiative competitors, which can explain the experimental quenching of W and X lines even in the presence of the photoluminescence centers.
eng
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http://creativecommons.org/licenses/by-nc-nd/4.0/
Attribution-NonCommercial-NoDerivatives 4.0 International
W and X Photoluminescence Centers in Crystalline Si: Chasing Candidates at Atomic Level Through Multiscale Simulations
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/309822021-06-24T07:18:55Zcom_10324_1148com_10324_931com_10324_894com_10324_28025com_10324_954col_10324_1270col_10324_28026
Santos Tejido, Iván
Ruiz Prieto, Manuel
Aboy Cebrián, María
Marqués Cuesta, Luis Alberto
López Martín, Pedro
Pelaz Montes, María Lourdes
2018-07-27T08:50:00Z
2018-07-27T08:50:00Z
2018
Journal of Electronic Materials, 2018, Volume 47, Issue 9, pp 4955–4958
0361-5235
http://uvadoc.uva.es/handle/10324/30982
https://doi.org/10.1007/s11664-018-6140-x
We used atomistic simulation tools to correlate experimental transmission electron microscopy images of extended defects in crystalline silicon with their structures at an atomic level. Reliable atomic configurations of extended defects were generated using classical molecular dynamics simulations. Simulated high-resolution transmission electron microscopy (HRTEM) images of obtained defects were compared to experimental images reported in the literature. We validated the developed procedure with the configurations proposed in the literature for {113} and {111} rod-like defects. We also proposed from our procedure configurations for {111} and {001} dislocation loops with simulated HRTEM images in excellent agreement with experimental images.
eng
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
Attribution-NonCommercial-NoDerivatives 4.0 International
Identification of Extended Defect Atomic Configurations in Silicon Through Transmission Electron Microscopy Image Simulation
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/319602021-06-24T07:19:10Zcom_10324_1148com_10324_931com_10324_894com_10324_28025com_10324_954col_10324_1270col_10324_28026
Santos Tejido, Iván
Marqués Cuesta, Luis Alberto
Pelaz Montes, María Lourdes
López Martín, Pedro
Aboy Cebrián, María
2018-10-02T07:21:30Z
2018-10-02T07:21:30Z
2012
AIP Conference Proceedings, 2012, Volume 1496, 229
0094-243X
http://uvadoc.uva.es/handle/10324/31960
https://doi.org/10.1063/1.4766530
We have studied the temperature effect on the damage generation mechanisms in silicon, suppressing the influence of dynamic annealing. We have done dedicated classical molecular dynamics simulations to determine how the ballistic mechanism and the thermal spikes are affected by temperature. We have quantified the minimum energy required to permanently displace an atom from its lattice position by a ballistic collision. We have found that the displacement energy threshold does not change appreciably with temperature. However, when subthreshold energy is simultaneously deposited in several neighboring particles in a finite volume, i.e. when thermal spikes occur, there is an enhancement of the generation of damage with increasing temperature. In high energy recoils both mechanisms are combined, and it results in an increase of the generated damage with temperature.
eng
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
Attribution-NonCommercial-NoDerivatives 4.0 International
Temperature effect on damage generation mechanisms during ion implantation in Si. A classical molecular dynamics study
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/319612021-06-24T07:19:06Zcom_10324_1148com_10324_931com_10324_894com_10324_28025com_10324_954col_10324_1270col_10324_28026
Aboy Cebrián, María
Pelaz Montes, María Lourdes
Bruno, Elena
Mirabella, Salvo
Boninelli, Simona
2018-10-02T07:55:27Z
2018-10-02T07:55:27Z
2011
Journal of Applied Physics 110, 073524 (2011)
0021-8979
http://uvadoc.uva.es/handle/10324/31961
https://doi.org/10.1063/1.3639280
We present an extended model for B clustering in crystalline or in preamorphized Si and with validity under conditions below and above the equilibrium solid solubility limit of B in Si. This model includes boron-interstitial clusters (BICs) with BnIm configurations—complexes with n B atoms and m Si interstitials—larger (n > 4), and eventually more stable, than those included in previous models. In crystalline Si, the formation and dissolution pathways into large BICs configurations require high B concentration and depend on the flux of Si interstitials. In the presence of high Si interstitial flux, large BICs with a relatively large number of interstitials (m ≥ n) are formed, dissolving under relatively low thermal budgets. On the contrary, for low Si interstitial flux large BICs with few interstitials (m ≪ n) can form, which are more stable than small BICs, and whose complete dissolution requires very intense thermal budgets. We have also investigated the kinetics of large BICs in preamorphized Si, both experimentally and theoretically. B was implanted at a high-dose into preamorphized Si, and the B precipitation was studied by transmission electron microscopy and by sheet resistance and Hall measurement techniques. A simplified model for B clustering and redistribution in amorphous Si is proposed, including the experimental value for the B diffusivity in amorphous Si and the energetics of BICs. Our model suggests that B2, B3I, B4I and B4I2 clusters are the most energetically favored configurations, with relative abundance depending on B concentration. After recrystallization, thermal anneals up to 1100 °C evidence that BICs evolve under very low flux of Si interstitials under the particular experimental conditions considered. Simulations indicate that for very high B concentrations and low Si interstitial flux a significant fraction of the initial small BICs evolves into larger and very stable BIC configurations that survive even after intense thermal budgets, as confirmed by energy filtered transmission electron microscopy analyses. The correlation between simulations and Hall measurements on these samples suggest that hole mobility is significantly degraded by the presence of a high concentration of BICs.
eng
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2011 American Institute of Physics
Attribution-NonCommercial-NoDerivatives 4.0 International
Kinetics of large B clusters in crystalline and preamorphized silicon
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/319622021-06-24T07:18:33Zcom_10324_1148com_10324_931com_10324_894com_10324_28025com_10324_954col_10324_1270col_10324_28026
Duffy, Ray
Shayesteh, M.
McCarthy, B.
Blake, A.
White, M.
Scully, J.
Yu, R.
Kelleher, A. M.
Schmidt, M.
Petkov, N.
Pelaz Montes, María Lourdes
Marqués Cuesta, Luis Alberto
2018-10-02T08:41:56Z
2018-10-02T08:41:56Z
2011
Applied Physics Letters, 2011, 99, 131901
0003-6951
http://uvadoc.uva.es/handle/10324/31962
https://doi.org/10.1063/1.3643160
The authors investigate the templated crystallization of thin-body Ge fin structures with high aspect ratios. Experimental variables include fin thickness and thermal treatments, with fin structures oriented in the 〈110〉 direction. Transmission electron microscopy determined that various crystal defects form during crystallization of amorphous Ge regions, most notably {111} stacking faults, twin boundaries, and small crystallites. In all cases, the nature of the defects is dependent on the fin thickness and thermal treatments applied. Using a standard 600 °C rapid-thermal-anneal, Gestructures with high aspect ratios crystallize with better crystal quality and fewer uncured defects than the equivalent Si case, which is a cause for optimism for thin-film Ge devices.
eng
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2011 American Institute of Physics
Attribution-NonCommercial-NoDerivatives 4.0 International
The curious case of thin-body Ge crystallization
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/319632021-06-24T07:18:31Zcom_10324_1148com_10324_931com_10324_894com_10324_28025com_10324_954col_10324_1270col_10324_28026
Santos Tejido, Iván
Pelaz Montes, María Lourdes
Marqués Cuesta, Luis Alberto
Colombo, Luciano
2018-10-02T09:30:37Z
2018-10-02T09:30:37Z
2011
Physical Review B, 2011, 83, 153201
2469-9950
http://uvadoc.uva.es/handle/10324/31963
https://doi.org/10.1103/PhysRevB.83.153201
We have analyzed the atomic rearrangements underlying self-diffusion in amorphous Si during annealing using tight-binding molecular dynamics simulations. Two types of amorphous samples with different structural features were used to analyze the influence of coordination defects. We have identified several types of atomic rearrangement mechanisms, and we have obtained an effective migration energy of around 1 eV. We found similar migration energies for both types of samples, but higher diffusivities in the one with a higher initial percentage of coordination defects.
eng
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2011 American Physical Society
Attribution-NonCommercial-NoDerivatives 4.0 International
Elucidating the atomistic mechanisms driving self-diffusion of amorphous Si during annealing
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/319642021-06-24T07:18:29Zcom_10324_1148com_10324_931com_10324_894com_10324_28025com_10324_954col_10324_1270col_10324_28026
Pelaz Montes, María Lourdes
Marqués Cuesta, Luis Alberto
Aboy Cebrián, María
Santos Tejido, Iván
López Martín, Pedro
Duffy, Ray
2018-10-02T10:33:58Z
2018-10-02T10:33:58Z
2010
Journal of Vacuum Science & Technology B, 2010, 28, C1A1-C1A6
2166-2746
http://uvadoc.uva.es/handle/10324/31964
https://doi.org/10.1116/1.3231481
Ion implantation continues being the dominant technique to introduce dopants in Si devices. With the device feature size in the nanometer scale, the accurate and detailed description of as-implanted dopant and damage profiles is becoming key as advanced annealing techniques are almost diffusionless. The demanding requirements for ultrashallow junction formation are stimulating the development of improved and detailed models for molecular implants and for the kinetics of amorphous damage. Additional challenges arise in the doping of advanced architectures, such as fin field effect transistors, because the introduction of highly tilted ions is quite inefficient and, in addition, the regrowth of amorphous regions in narrow structures is hampered by the slow regrowth at free interfaces and {111} planes. Atomistic simulations play a relevant role to provide the understanding for the development of simplified physically based models computationally more efficient.
eng
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2010 American Vacuum Society
Attribution-NonCommercial-NoDerivatives 4.0 International
Simulation of p-n junctions: Present and future challenges for technologies beyond 32 nm
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/319652021-06-24T07:18:28Zcom_10324_1148com_10324_931com_10324_894com_10324_28025com_10324_954col_10324_1270col_10324_28026
Santos Tejido, Iván
Castrillo, P.
Windl, W.
Drabold, D. A.
Pelaz Montes, María Lourdes
Marqués Cuesta, Luis Alberto
2018-10-02T11:00:44Z
2018-10-02T11:00:44Z
2010
Physical Review B, 2010, 81, 033203
2469-9950
http://uvadoc.uva.es/handle/10324/31965
https://doi.org/10.1103/PhysRevB.81.033203
We have used ab initio simulations to study the doping efficiency of amorphous semiconductors, in particular of B-doped amorphous Si. We have found that even in the optimum case of substitutional doping in dangling-bond free amorphous Si the holes provided by B atoms do not behave as free carriers. Instead, they are trapped into regions with locally distorted bond angles. Thus, the effective activation energy for hole conduction turns to be the hole binding energy to these traps. In the case of high B concentration, the trap states move deeper in the gap and the binding energy and spatial localization of holes increase. In addition, B atoms have lower energies for shorter bond lengths, configurations favored in the vicinity of these traps.
eng
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2010 The American Physical Society
Attribution-NonCommercial-NoDerivatives 4.0 International
Self-trapping in B-doped amorphous Si: Intrinsic origin of low acceptor efficiency
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/319662021-05-21T21:09:47Zcom_10324_28025com_10324_954com_10324_894com_10324_1148com_10324_931col_10324_28026col_10324_1270
Aboy Cebrián, María
Pelaz Montes, María Lourdes
López Martín, Pedro
Bruno, Elena
Mirabella, Salvo
2018-10-02T11:17:13Z
2018-10-02T11:17:13Z
2010
International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 23, 266 (2010)
0894-3370
http://uvadoc.uva.es/handle/10324/31966
https://doi.org/10.1002/jnm.737
In this paper we discuss from an atomistic point of view some of the issues involved in the modeling of electrical characteristics evolution in silicon devices as a result of ion implantation and annealing processes in silicon. In particular, evolution of electrically active dose, sheet resistance and hole mobility has been investigated for high B concentration profiles in pre‐amorphized Si. For this purpose, Hall measurements combined with atomistic kinetic Monte Carlo atomistic simulations have been performed. An apparent anomalous behavior has been observed for the evolution of the active dose and the sheet resistance, in contrast to opposite trend evolutions reported previously. Our results indicate that this anomalous behavior is due to large variations in hole mobility with active dopant concentration, much larger than that associated to the classical dependence of hole mobility with carrier concentration. Simulations suggest that hole mobility is significantly degraded by the presence of a large concentration of boron‐interstitial clusters, indicating the existence of an additional scattering mechanism. Copyright © 2009 John Wiley & Sons, Ltd.
eng
info:eu-repo/semantics/openAccess
© 2009 John Wiley & Sons, Ltd.
Atomistic analysis of B clustering and mobility degradation in highly B-doped junctions
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/324002021-06-24T07:19:07Zcom_10324_1148com_10324_931com_10324_894com_10324_28025com_10324_954col_10324_1270col_10324_28026
Santos Tejido, Iván
Aboy Cebrián, María
Marqués Cuesta, Luis Alberto
López Martín, Pedro
Pelaz Montes, María Lourdes
2018-10-31T07:53:59Z
2018-10-31T07:53:59Z
2018
Journal of Non-Crystalline Solids, 2019, Volumes 503–504, Pages 20-27
0022-3093
http://uvadoc.uva.es/handle/10324/32400
https://doi.org/10.1016/j.jnoncrysol.2018.09.024
Journal of Non-Crystalline Solids
The construction of realistic atomistic models for amorphous solids is complicated by the fact that they do not have a unique structure. Among the different computational procedures available for this purpose, the melting and rapid quenching process using molecular dynamics simulations is commonly employed as it is simple and physically based. Nevertheless, the cooling rate used during quenching strongly affects the reliability of generated samples, as fast cooling rates result in unrealistic atomistic models. In this study, we have determined the conditions to be fulfilled when simulating the quenching process with molecular dynamics for obtaining amorphous Si (a-Si) atomistic models structurally compatible with experimental samples. We have analyzed the structure of samples generated with cooling rates ranging from 3.3 1010 to 8.5 1014 K/s. The obtained results were compared with experimental data available in the literature, and with samples generated by other state-of-the-art and more sophisticated computational procedures. For cooling rates below 1011 K/s, a-Si samples generated had structural parameters within the range of experimental samples, and comparable to those obtained from other refined modeling procedures. These computationally slow cooling rates are of the same order of magnitude than those experimentally achieved with pulsed energy melting techniques. Samples obtained with faster cooling rates can be further relaxed with annealing simulations, resulting in structural parameters within the range of experimental samples. Nevertheless, the required annealing times are on the order of microseconds, which makes this annealing step non practical from a computational point of view.
eng
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
Attribution-NonCommercial-NoDerivatives 4.0 International
Generation of amorphous Si structurally compatible with experimental samples through the quenching process: A systematic molecular dynamics simulation study
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/324052021-06-24T07:19:08Zcom_10324_28025com_10324_954com_10324_894com_10324_1148com_10324_931col_10324_28026col_10324_1270
Marqués Cuesta, Luis Alberto
Aboy Cebrián, María
Santos Tejido, Iván
López Martín, Pedro
Cristiano, Fuccio
La Magna, Antonino
Huet, Karim
Tabata, Toshiyuki
Pelaz Montes, María Lourdes
2018-10-31T11:06:47Z
2018-10-31T11:06:47Z
2018
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2018, Volume 458, Pages 179-183
http://uvadoc.uva.es/handle/10324/32405
https://doi.org/10.1016/j.nimb.2018.09.030
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms
We combine focused experiments with molecular dynamics simulations to investigate in detail the formation of {001} loops in nanosecond laser-annealed silicon. We demonstrate that at temperatures close to the melting point, self-interstitial rich silicon is driven into dense liquid-like droplets that are highly mobile within the solid crystalline matrix. These liquid droplets grow by a coalescence mechanism and eventually transform into {0 0 1} loops through a liquid-to-solid phase transition in the nanosecond timescale.
eng
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
Attribution-NonCommercial-NoDerivatives 4.0 International
On the anomalous generation of {0 0 1} loops during laser annealing of ion-implanted silicon
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/336062021-06-23T10:09:12Zcom_10324_1148com_10324_931com_10324_894col_10324_1270
Barba García, Ismael
Molina Cuberos, Gregorio José
García Collado, Ángel J.
Represa Fernández, José Benito
López Cabeceira, Ana Cristina
2018-12-21T09:14:24Z
2018-12-21T09:14:24Z
2018
International Journal of Antennas and Propagation 2018, Article ID 4198243, 6 pages
1687-5869
http://uvadoc.uva.es/handle/10324/33606
https://doi.org/10.1155/2018/4198243
A uniaxial bianisotropic, full-dielectric structure has been designed and numerically studied. The material is based on a previously published 2D-honeycomb structure. A 3D expansion leads to an effective metamaterial showing a typical chiral electromagnetic behavior, i.e., a resonant electromagnetic activity with a small circular dichroism.
eng
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
Attribution-NonCommercial-NoDerivatives 4.0 International
A Full-Dielectric Chiral Material Based on a Honeycomb Structure
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/336102021-06-23T10:09:13Zcom_10324_1148com_10324_931com_10324_894col_10324_1270
Pereda, José A.
Grande Sáez, Ana María
2018-12-21T09:48:46Z
2018-12-21T09:48:46Z
2017
IEEE Antennas and Wireless Propagation Letters, 2017, Volume 16, pp. 2122-2125
1536-1225
http://uvadoc.uva.es/handle/10324/33610
https://doi.org/10.1109/LAWP.2017.2699692
A closed-form expression is derived for the numerical dispersion relation of the 2-D locally one-dimensional finite-difference time-domain (LOD-FDTD) method in lossy media. In contrast to the lossless formulation, we found that transverse-electric (TEz) and transverse-magnetic (TM z ) waves in lossy media exhibit different numerical dispersion relations. Moreover, when the material relaxation-time constant is not well resolved by the integration time-step, the TM z case shows much worse accuracy than the TE z case. To remove this limitation, a split-field LOD-FDTD formulation for TM z waves is then considered, which exhibits the same dispersion relation as the LOD-FDTD method for TE z waves. The validity of the theoretical results is illustrated through numerical simulations.
eng
info:eu-repo/semantics/openAccess
© 2017 IEEE
Numerical Dispersion Relation for the 2-D LOD-FDTD Method in Lossy Media
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/336122021-06-23T10:09:13Zcom_10324_1148com_10324_931com_10324_894col_10324_1270
Pereda, José A.
Grande Sáez, Ana María
2018-12-21T10:01:43Z
2018-12-21T10:01:43Z
2018
IEEE Microwave and Wireless Components Letters, 2018, Volume 28 , Issue 6, pp. 461-463
1531-1309
http://uvadoc.uva.es/handle/10324/33612
https://doi.org/10.1109/LMWC.2018.2832014
The electric field computed by the locally 1-D finite-difference time-domain (FDTD) method at dielectric interfaces is investigated. To this end, two comprehensive problems are considered, namely a dielectric step in a rectangular waveguide and a dielectric-loaded metallic cavity. We found that, in both problems, the electric field patterns exhibit an unexpected phase shift at the dielectric interface. By contrast, the alternating-direction implicit FDTD method does not present this unphysical behavior.
eng
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2018 IEEE
Attribution-NonCommercial-NoDerivatives 4.0 International
On the Behavior of the LOD-FDTD Method at Dielectric Interfaces
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/336142021-06-23T10:09:14Zcom_10324_1148com_10324_931com_10324_894col_10324_1270
García Collado, Ángel J.
Molina Cuberos, Gregorio José
Margineda, José
Barba García, Ismael
2018-12-21T11:15:55Z
2019
IET Microwaves, Antennas and Propagation (in press)
1751-8725
http://uvadoc.uva.es/handle/10324/33614
A new chiral material composed of a two-dimensional lattice of five-segment cranks, with the same handedness is experimentally and numerically studied. The sample, formed by a single layer of such structures, exhibits huge electromagnetic activity and a negative refraction index for linearly polarized waves. Both the chirality parameter and the bandwidth with the
negative refraction index are larger than those observed in chiral media composed of three-segment cranks. The material also shows pronounced electromagnetic activity (larger than 500 per wavelength). This observed behaviour is attributed to the fact that the five-segment configuration enhances the electromagnetic coupling compared with the three-segment configuration.
eng
info:eu-repo/semantics/openAccess
© Institution of Engineering and Technology
Large Electromagnetic Activity Metamaterial Composed of Five-Segment Cranks
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/337292021-06-24T07:19:11Zcom_10324_1148com_10324_931com_10324_894com_10324_28025com_10324_954col_10324_1270col_10324_28026
Marqués Cuesta, Luis Alberto
Aboy Cebrián, María
Ruiz Prieto, Manuel
Santos Tejido, Iván
López Martín, Pedro
Pelaz Montes, María Lourdes
2019-01-09T08:44:09Z
2019
Acta Materialia, 2019, Volume 166, Pages 192-201
http://uvadoc.uva.es/handle/10324/33729
https://doi.org/10.1016/j.actamat.2018.12.052
By using classical molecular dynamics simulations and a novel technique to identify defects based on the calculation of atomic strain, we have elucidated the detailed mechanisms leading to the anomalous generation and growth of {001} loops found after ultra-fast laser annealing of ion-implanted Si. We show that the building block of the {001} loops is the very stable Arai tetra-interstitial [N. Arai, S. Takeda, M. Kohyama, Phys. Rev. Lett. 78, 4265 (1997)], but their growth is kinetically prevented within conventional Ostwald ripening mechanisms under standard processing conditions. However, our simulations predict that at temperatures close to the Si melting point, Arai tetra-interstitials directly nucleate at the boundaries of fast diffusing self-interstitial agglomerates, which merge by a coalescence mechanism reaching large sizes in the nanosecond timescale. We demonstrate that the crystallization of such agglomerates into {001} loops and their subsequent growth is mediated by the tensile and compressive strain fields that develop concurrently around the loops. We also show that further annealing produces the unfaulting of {001} loops into perfect dislocations. Besides, from the simulations we have fully characterized the {001} loops, determining their atomic structure, interstitial density and formation energy.
eng
info:eu-repo/semantics/openAccess
© 2018 Elsevier
{001} loops in silicon unraveled
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/451242022-08-16T11:05:21Zcom_10324_28025com_10324_954com_10324_894com_10324_1148com_10324_931col_10324_28026col_10324_1270
Tsai, Chun-Hsiung
Hsu, Yu-Hsiang
Santos Tejido, Iván
Pelaz Montes, María Lourdes
Kowalski, Jeffrey
Liou, J.W.
Woon, Wei-Yen
Lee, Chih-Kung
2021-01-25T08:34:21Z
2021-01-25T08:34:21Z
2021
Materials Science in Semiconductor Processing Volume 127, 2021, 105672
1369-8001
http://uvadoc.uva.es/handle/10324/45124
10.1016/j.mssp.2021.105672
105672
Materials Science in Semiconductor Processing
127
Junction stability and donor deactivation in silicon at high doping limit has been a long-standing issue in advanced semiconductor devices. Recently, heavily doped epitaxial Si:P layer with phosphorus concentrations as high as 3 × 1021 at./cm3 has been employed in nanowire field-effect transistor (FET) devices for sub-3 nm technology node as low resistance source-drain and channel stressor. In such highly doped Si:P, the actual dopant activation is much less than nominal phosphorus concentration due to inactive phosphorus atoms arising from dopant-vacancy defects (PnV) clustering phenomenon. Even with state-of-the-art high temperature millisecond annealing, this epitaxial film is thermally unstable upon subsequent thermal treatments. To overcome this limitation, we demonstrate a selective dopant activation scheme which results from the dipole moments of inactive PnV structures within the crystal lattice and their direct energy coupling with the external electric field. It's found that superior stability in dopant activation can be achieved through microwave annealing when a specific temperature and field conditions are met using a triple-parallel-susceptor setup in the microwave cavity. Based on experimental results and ab-initio calculation, we proposed a model, whereas the microwave-PnV interactions result in a specific distribution of dopant defect dominated by thermally stable P4V clusters through elimination of unstable low order PnV, leading to the suppression of donor deactivation and achieving thermally stable junction.
eng
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
Achieving junction stability in heavily doped epitaxial Si:P
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/511362022-07-18T09:32:50Zcom_10324_1148com_10324_931com_10324_894com_10324_28025com_10324_954col_10324_1270col_10324_28026
López Martín, Pedro
Aboy Cebrián, María
Muñoz Velasco, Irene
Santos Tejido, Iván
Marqués Cuesta, Luis Alberto
Fernández Martínez, Pablo
Ullán, Miguel
Pelaz Montes, María Lourdes
2021-12-22T11:43:43Z
2021-12-22T11:43:43Z
2022
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2022, vol. 512, p. 42-48
0168-583X
https://uvadoc.uva.es/handle/10324/51136
10.1016/j.nimb.2021.12.003
42
48
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms
512
The effective dopant concentration in p-type Si detectors reduces with irradiation fluence at low fluences due to the acceptor removal process, which degrades detector performance and shortens its lifetime. This effect has been experimentally characterized and parametrized, but its microscopic origin is still unknown. We use atomistic simulations to gain insight into acceptor removal in neutron irradiation by modeling damage generation and defect-dopant interactions. We analyze the effect on dopant deactivation of the Si di- and tri-interstitial diffusion, the inhomogeneity of irradiation damage and the wafer temperature rise during irradiation. We characterize defect generation rates and identify the relevant defect-dopant interactions. Acceptor removal occurs mainly through the formation of Bi pairs and small boron-interstitial clusters, and it is limited by the availability of mobile Si interstitials. The presence of impurities (O, C) modifies B-complexes favoring the formation of BiO, but has a limited effect on the amount of removed acceptors.
eng
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/4.0/
© 2021 The Authors
Atribución 4.0 Internacional
Atomistic simulations of acceptor removal in p-type Si irradiated with neutrons
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/511372022-01-05T12:33:59Zcom_10324_1148com_10324_931com_10324_894com_10324_28025com_10324_954col_10324_1270col_10324_28026
Santos Tejido, Iván
Caballo Zulueta, Ana
Aboy Cebrián, María
Marqués Cuesta, Luis Alberto
López Martín, Pedro
Pelaz Montes, María Lourdes
2021-12-22T12:01:59Z
2021-12-22T12:01:59Z
2022
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2022, vol. 512, p. 54-59
0168-583X
https://uvadoc.uva.es/handle/10324/51137
10.1016/j.nimb.2021.12.002
54
59
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms
512
Emergent alternative Si processes and devices have promoted applications outside the usual processing temperature window and the failure of traditional defect kinetics models. These models are based on Ostwald ripening mechanisms, assume pre-established defect configurations and neglect entropic contributions. We performed molecular dynamics simulations of self-interstitial clustering in Si with no assumptions on preferential defect configurations. Relevant identified defects were characterized by their formation enthalpy and vibrational entropy calculated from their local vibrational modes. Our calculations show that entropic terms are key to understand defect kinetics at high temperature. We also show that for each cluster size, defect configurations may appear in different crystallographic orientations and transformations among these configurations are often hampered by energy barriers. This induces the presence of non-expected small-size defect cluster configurations that could be associated to optical signals in low temperature processes. At high temperatures, defect dynamics entails mobility and ripening through a coalescence mechanism.
eng
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/4.0/
© 2021 The Authors
Atribución 4.0 Internacional
Extending defect models for Si processing: The role of energy barriers for defect transformation, entropy and coalescence mechanism
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/543892022-10-03T12:51:24Zcom_10324_28025com_10324_954com_10324_894com_10324_1148com_10324_931col_10324_28026col_10324_1270
Tsai, Chun-Hsiung
Savant, Chandrashekhar P.
Asadi, Mohammad Javad
Lin, Yu-Ming
Santos Tejido, Iván
Hsu, Yu-Hsiang
Kowalski, Jeffrey
Pelaz Montes, María Lourdes
Woon, Wei-Yen
Lee, Chih-Kung
Hwang, James C. M.
2022-08-16T10:52:16Z
2022-08-16T10:52:16Z
2022
Applied Physics Letters, 2022, vol. 121, n. 5, 052103
0003-6951
https://uvadoc.uva.es/handle/10324/54389
10.1063/5.0099083
052103
5
Applied Physics Letters
121
1077-3118
The relentless scaling of semiconductor devices pushes the doping level far above the equilibrium solubility, yet the doped material must be sufficiently stable for subsequent device fabrication and operation. For example, in epitaxial silicon doped above the solubility of phosphorus, most phosphorus dopants are compensated by vacancies, and some of the phosphorus-vacancy clusters can become mobile around 700 °C to further cluster with isolated phosphorus ions. For efficient and stable doping, we use microwave annealing to selectively activate metastable phosphorus-vacancy clusters by interacting with their dipole moments, while keeping lattice heating below 700 °C. In a 30-nm-thick Si nanosheet doped with 3 × 1021 cm−3 phosphorus, a microwave power of 12 kW at 2.45 GHz for 6 min resulted in a free-electron concentration of 4 × 1020 cm−3 and a junction more abrupt than 4 decades/nm. The doping profile is stable with less than 4% variation upon thermal annealing around 700 °C for 5 min. Thus, microwave annealing can result in not only efficient activation and abrupt profile in epitaxial silicon but also thermal stability. In comparison, conventional rapid thermal annealing can generate a junction as abrupt as microwave annealing but 25% higher sheet resistance and six times higher instability at 700 °C.
eng
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2020 The Authors
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
Efficient and stable activation by microwave annealing of nanosheet silicon doped with phosphorus above its solubility limit
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/551592023-12-31T21:00:25Zcom_10324_28025com_10324_954com_10324_894com_10324_1148com_10324_931col_10324_28026col_10324_1270
Tsai, Chinhao
Aboy Cebrián, María
Pelaz Montes, María Lourdes
Hsu, Yu-Hsiang
Woon, Wei-Yen
Timans, Paul J.
Lee, Chih-Kung
2022-09-16T11:26:38Z
2022-09-16T11:26:38Z
2022
Materials Science in Semiconductor Processing, 2022, vol. 152, 107052
1369-8001
https://uvadoc.uva.es/handle/10324/55159
10.1016/j.mssp.2022.107052
Intra-die device variation due to pattern layout effects associated with the development of ultra-fast annealing processes is one of the major scaling challenges for advanced CMOS devices. In this paper, we show that an excellent and universal correlation can be established between on-die device variation and a new reflectance characterization technique with sufficient resolution. This approach has the potential to be universally applicable to virtually any structure pattern. In addition, we conducted simulations of the thermal annealing effect on 2D doping profiles by considering the effects of temperature sensitivity, reflectivity, and active dopant fraction. Our results show that the observed on-die variation was caused mainly by using a rapid thermal annealing (RTA) process rather than by flash annealing (FLA). We further concluded that pattern-induced device variation is mainly due to the redistribution of the dopants, instead of from dopant activation. To mitigate the pattern loading effect from thermal annealing, we employed a light absorbing layer to eliminate the within-die reflectivity variation. We found that we could successfully reduce electrical on-die variation by 50%.
eng
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2022 Elsevier
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
Rapid thermal process driven intra-die device variations
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/556032022-10-17T19:00:20Zcom_10324_28025com_10324_954com_10324_894com_10324_1148com_10324_931col_10324_28026col_10324_1270
López Martín, Pedro
Aboy Cebrián, María
Santos Tejido, Iván
Marqués Cuesta, Luis Alberto
Ullán, Miguel
Pelaz Montes, María Lourdes
2022-09-23T08:09:18Z
2022-09-23T08:09:18Z
2022
Acta Materialia, 2022, vol. 141, 118375
1359-6454
https://uvadoc.uva.es/handle/10324/55603
10.1016/j.actamat.2022.118375
The improved radiation hardness of p-type Si detectors is hindered by the radiation-induced acceptor removal process, which is not fully understood yet. Through atomistic modeling of displacement damage and dopant interactions, we analyze the acceptor removal under neutron irradiation, providing physical insight into its microscopic origin. Our results show that the fast decay of the effective dopant concentration (Neff) at low irradiation fluences is due to B deactivation caused by Si self-interstitials. The intriguing increase of the acceptor removal parameter with the initial dopant concentration (Neff,0) is explained by the limited number of mobile Si self-interstitials that survive annihilation and clustering processes. The sublinear dependence of the removal parameter on Neff,0 is associated to the inhomogeneity of damage for low Neff,0 and the formation of B-interstitial clusters with several B atoms for high Neff,0. The presence of O and C modifies B deactivation mechanisms due to the key role of BiO defects and the trapping of vacancies and Si self-interstitials, but for the impurity concentrations analyzed in this work ([O] >> [C]) it has little effect on the overall amount of removed acceptors. At high irradiation fluences, the reported increase of Neff is attributed to the formation of defect-related deep acceptors. From the analysis of the defect concentrations resulting from neutron irradiation and the occupancy of small clusters with acceptor levels reported in literature, we point out the tetra-vacancy cluster as one of the main contributors to Neff with negative space charge.
eng
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/3.0/
© 2022 The Authors
Attribution 3.0 Unported
Microscopic origin of the acceptor removal in neutron-irradiated Si detectors - An atomistic simulation study
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/586432023-02-13T20:00:21Zcom_10324_1148com_10324_931com_10324_894col_10324_1270
García García, Héctor
Jiménez Molinos, Francisco
Vinuesa Sanz, Guillermo
Bargalló González, Mireia
Roldán, Juan B.
Miranda, Enrique
Campabadal Segura, Francesca
Castán Lanaspa, María Helena
Dueñas Carazo, Salvador
2023-02-13T14:10:31Z
2023-02-13T14:10:31Z
2022
Solid-State Electronics, 2022, vol. 194, p. 108385
0038-1101
https://uvadoc.uva.es/handle/10324/58643
10.1016/j.sse.2022.108385
108385
Solid-State Electronics
194
In this work, we have studied the control of set and the reset transitions in TiN/Ti/HfO2/W resistive switching devices using a new approach based on the injection of a limited amount of charge through the use of a capacitor discharge. Instead of applying conventional voltage or current signals, the capacitor discharge through the devices is able to perform both transitions. An accumulative process is observed if we apply consecutive discharges, and, when increasing the capacitor voltage in each discharge, the transitions between both resistance states are completed. In addition, it has been shown that faster transitions require larger capacitor voltages. Further, the electrical results were used to tune the dynamic memdiode model, which was employed to simulate set and reset processes driven by the capacitor discharges. The model successfully reproduced the measured memristor response to the capacitor discharge.
eng
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2022 The Author(s)
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
Study of TiN/Ti/HfO2/W resistive switching devices: characterization and modeling of the set and reset transitions using an external capacitor discharge
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/589412023-03-15T20:00:27Zcom_10324_1148com_10324_931com_10324_894col_10324_1270
Pérez, Eduardo
González Ossorio, Óscar
Dueñas Carazo, Salvador
Castán Lanaspa, María Helena
García García, Héctor
Wenger, Christian
2023-03-15T12:36:31Z
2023-03-15T12:36:31Z
2020
Electronics, 2020, vol. 9, n.5, 864
https://uvadoc.uva.es/handle/10324/58941
10.3390/electronics9050864
864
5
Electronics
9
2079-9292
A crucial step in order to achieve fast and low-energy switching operations in resistive random access memory (RRAM) memories is the reduction of the programming pulse width. In this study, the incremental step pulse with verify algorithm (ISPVA) was implemented by using different pulse widths between 10 μs and 50 ns and assessed on Al-doped HfO2 4 kbit RRAM memory arrays. The switching stability was assessed by means of an endurance test of 1k cycles. Both conductive levels and voltages needed for switching showed a remarkable good behavior along 1k reset/set cycles regardless the programming pulse width implemented. Nevertheless, the distributions of voltages as well as the amount of energy required to carry out the switching operations were definitely affected by the value of the pulse width. In addition, the data retention was evaluated after the endurance analysis by annealing the RRAM devices at 150 °C along 100 h. Just an almost negligible increase on the rate of degradation of about 1 μA at the end of the 100 h of annealing was reported between those samples programmed by employing a pulse width of 10 μs and those employing 50 ns. Finally, an endurance performance of 200k cycles without any degradation was achieved on 128 RRAM devices by using programming pulses of 100 ns width.
eng
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/4.0/
© 2020 The Authors
Atribución 4.0 Internacional
Electrónica
Electricidad
RRAM
Programming pulse width assessment for reliable and low-energy endurance performance in Al:HfO2-Based RRAM arrays
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/589742023-06-01T09:03:56Zcom_10324_28025com_10324_954com_10324_894com_10324_1148com_10324_931col_10324_28026col_10324_1270
Martín Encinar, Luis
Marqués Cuesta, Luis Alberto
Santos Tejido, Iván
López Martín, Pedro
Pelaz Montes, María Lourdes
2023-03-20T08:47:16Z
2023-03-20T08:47:16Z
2023
Advanced Theory and Simulations, 2023, Volume 6, Issue5, 2200848
2513-0390
https://uvadoc.uva.es/handle/10324/58974
10.1002/adts.202200848
2200848
Advanced Theory and Simulations
2513-0390
The surface diffusion and intermixing of Ge ad-atoms over Si (001) 2 × 1 substrates using classical molecular dynamics (CMD) simulations are characterized here. Several interatomic potentials, parametrizations, and parameter mixing rules are contemplated. A novel simulation scheme is devised to characterize the effective frequency of surface diffusion and intermixing events overcoming the inherent difficulties related to their interdependency in heteroepitaxial systems. The effective energy barriers of these events encompass different atomistic mechanisms weighted by their occurrence probabilities. The overall description of surface diffusion and intermixing based on Stillinger–Weber (SW) potential is in agreement with ab initio calculations and experimental observations, though some atomistic details differ. This study is extended to Si(001) substrates with stressed Ge monolayers grown on top. It is found that Ge ad-atom dynamics is accelerated with respect to the case of the pure Si substrate and that diffusion across dimer rows is mainly mediated by the atomic exchange of the Ge ad-atom with a Ge atom on the surface.
eng
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/4.0/
© 2023 The Author(s)
Atribución 4.0 Internacional
Concurrent characterization of surface diffusion and intermixing of Ge on Si: A classical molecular dynamics study
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/589782023-03-20T20:00:28Zcom_10324_1148com_10324_931com_10324_894col_10324_1270
Rosales Martínez, Antonio
Enríquez Giraudo, María Lourdes
Jaraíz Maldonado, Martín
Pozo Morales, Laura
Rodríguez García, Ignacio
Díaz Ojeda, Emilio
2023-03-20T12:01:33Z
2023-03-20T12:01:33Z
2020
Marine Drugs, 2020, Vol. 18, Nº. 9, 441
1660-3397
https://uvadoc.uva.es/handle/10324/58978
10.3390/md18090441
441
9
Marine Drugs
18
1660-3397
A new concise general methodology for the synthesis of different tetracyclic meroterpenoids is reported: (±)-aureol (1), the key intermediate of this general route. The synthesis of (±)-aureol (1) was achieved in seven steps (28% overall yield) from (±)-albicanol. The key steps of this route include a C–C bond-forming reaction between (±)-albicanal and a lithiated arene unit and a rearrangement involving 1,2-hydride and 1,2-methyl shifts promoted by BF3•Et2O as activator and water as initiator.
eng
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/4.0/
© 2020 The Authors
Atribución 4.0 Internacional
Natural products - Synthesis
Productos naturales
Química orgánica - Síntesis
A concise route for the synthesis of tetracyclic meroterpenoids: (±)-aureol preparation and mechanistic interpretation
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/590922023-04-12T19:00:34Zcom_10324_1148com_10324_931com_10324_894col_10324_1270
García García, Héctor
Boo Alvarez, Jonathan
Vinuesa Sanz, Guillermo
González Ossorio, Óscar
Sahelices Fernández, Benjamín
Dueñas Carazo, Salvador
Castán Lanaspa, María Helena
Bargalló González, Mireia
Campabadal Segura, Francesca
2023-04-12T12:07:19Z
2023-04-12T12:07:19Z
2021
Electronics, 2021, Vol. 10, Nº. 22, 2816
2079-9292
https://uvadoc.uva.es/handle/10324/59092
10.3390/electronics10222816
2816
22
Electronics
10
2079-9292
In the attempt to understand the behavior of HfO2-based resistive switching devices at low temperatures, TiN/Ti/HfO2/W metal–insulator–metal devices were fabricated; the atomic layer deposition technique was used to grow the high-k layer. After performing an electroforming process at room temperature, the device was cooled in a cryostat to carry out 100 current–voltage cycles at several temperatures ranging from the “liquid nitrogen temperature” to 350 K. The measurements showed a semiconducting behavior in high and low resistance states. In the low resistance state, a hopping conduction mechanism was obtained. The set and reset voltages increased when temperature decreased because the thermal energies for oxygen vacancies and ions were reduced. However, the temperature did not influence the power absorbed in the reset transition, indicating the local temperature in the filament controls the transition. The set transition turned from gradual to abrupt when decreasing the temperature, due to a positive feedback between the current increase and the Joule heating at low temperatures.
eng
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/4.0/
© 2021 The authors
Atribución 4.0 Internacional
Electric resistors
Switching circuits
Electronic Circuits and Devices
Influences of the temperature on the electrical properties of HfO2-based resistive switching devices
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/591552023-05-03T13:04:15Zcom_10324_1148com_10324_931com_10324_894col_10324_1270
Vinuesa Sanz, Guillermo
García García, Héctor
Lendínez Sánchez, José Miguel
García Ochoa, Eduardo
González, M. B.
Maldonado, D
Aguilera Pedregosa, C
Moreno, E
Jiménez Molinos, Francisco
Roldán, J.B.
Campabadal Segura, Francesca
Castán Lanaspa, María Helena
Dueñas Carazo, Salvador
2023-04-17T13:44:41Z
2023-04-17T13:44:41Z
2023
Microelectronic Engineering, 2023, vol. 276, 112008
0167-9317
https://uvadoc.uva.es/handle/10324/59155
10.1016/j.mee.2023.112008
112008
Microelectronic Engineering
In this work, the unipolar resistive switching behaviour of Ni/HfO2/Si(n+) devices is studied. The structures are characterized using both current and voltage sweeps, with the device resistance and its cycle-to-cycle variability being analysed in each case. Experimental measurements indicate a clear improvement on resistance states stability when using current sweeps to induce both set and reset processes. Moreover, it has been found that using current to induce these transitions is more efficient than using voltage sweeps, as seen when analysing the device power consumption. The same results are obtained for devices with a Ni top electrode and a bilayer or pentalayer of HfO2/Al2O3 as dielectric. Finally, kinetic Monte Carlo and compact modelling simulation studies are performed to shed light on the experimental results.
eng
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/4.0/
© 2023 The Authors
Atribución 4.0 Internacional
Electricidad
Electrónica
Computers
Variability and power enhancement of current controlled resistive switching devices
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/620512023-10-19T08:11:11Zcom_10324_1148com_10324_931com_10324_894col_10324_1270
Kalam, Kristjan
Otsus, Markus
Kozlova, Jekaterina
Tarre, Aivar
Kasikov, Aarne
Rammula, Raul
Link, Joosep
Stern, Raivo
Vinuesa Sanz, Guillermo
Lendínez Sánchez, José Miguel
Dueñas Carazo, Salvador
Castán Lanaspa, María Helena
Tamm, Aile
Kukli, Kaupo
2023-10-18T08:04:42Z
2023-10-18T08:04:42Z
2022
Nanomaterials, 2022, Vol. 12, Nº. 15, 2593
2079-4991
https://uvadoc.uva.es/handle/10324/62051
10.3390/nano12152593
2593
15
Nanomaterials
12
2079-4991
HfO2 and Fe2O3 thin films and laminated stacks were grown by atomic layer deposition at 350 °C from hafnium tetrachloride, ferrocene, and ozone. Nonlinear, saturating, and hysteretic magnetization was recorded in the films. Magnetization was expectedly dominated by increasing the content of Fe2O3. However, coercive force could also be enhanced by the choice of appropriate ratios of HfO2 and Fe2O3 in nanolaminated structures. Saturation magnetization was observed in the measurement temperature range of 5–350 K, decreasing towards higher temperatures and increasing with the films’ thicknesses and crystal growth. Coercive force tended to increase with a decrease in the thickness of crystallized layers. The films containing insulating HfO2 layers grown alternately with magnetic Fe2O3 exhibited abilities to both switch resistively and magnetize at room temperature. Resistive switching was unipolar in all the oxides mounted between Ti and TiN electrodes.
eng
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/4.0/
© 2022 The Authors
Atribución 4.0 Internacional
Thin films
Atomic layer deposition
Oxide
Hafnium
Iron oxides
Oxido ferroso
Nanoparticles
Nanoparticulas
Nanotechnology
Nanotecnología
Ferromagnetism
Magnetism
Magnetic materials
Materiales magnéticos
Resistive switching
Switching circuits
Circuitos eléctricos
Microelectronics
Memory effects in nanolaminates of hafnium and iron oxide films structured by atomic layer deposition
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/620922023-10-19T19:01:01Zcom_10324_1148com_10324_931com_10324_894col_10324_1270
Vinuesa Sanz, Guillermo
García García, Héctor
Bargalló González, Mireia
Kalam, Kristjan
Zabala, Miguel
Tarre, Aivar
Kukli, Kaupo
Tamm, Aile
Campabadal Segura, Francesca
Jiménez López, Juan Ignacio
Castán Lanaspa, María Helena
Dueñas Carazo, Salvador
2023-10-19T08:37:37Z
2023-10-19T08:37:37Z
2022
Electronics, 2022, Vol. 11, Nº. 3, 479
2079-9292
https://uvadoc.uva.es/handle/10324/62092
10.3390/electronics11030479
479
3
Electronics
11
2079-9292
In recent years, several materials and metal-insulator-metal devices are being intensively studied as prospective non-volatile memories due to their resistive switching effect. In this work, thickness-dependent resistive switching polarity was observed in TiN/Ti/HfO2/Pt structures as the sign of the voltages at which SET and RESET occur depended on the film thickness. A thorough revision of the previous literature on bipolar resistive switching polarity changes is made in order to condense previous knowledge of the subject in a brief and comprehensible way and explain the experimental measurements. The different resistive switching polarities occur in a similar voltage range, which is a new finding when compared to precedent research on the subject. A hypothesis is proposed to explain the change in resistive switching polarity, based on the assumption that polarity change is due to filament disruption occurring at different interfaces.
eng
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/4.0/
© 2022 The Authors
Atribución 4.0 Internacional
Resistive switching
Switching circuits
Circuitos eléctricos
Electric resistors
Resistencias eléctricas
Conductive filament
Nonvolatile random-access memory
Memoria de acceso aleatorio no volátil
Polarity
Oxide
Hafnium
Electronics
Electricity
Effect of dielectric thickness on resistive switching polarity in TiN/Ti/HfO2/Pt stacks
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/629182023-11-14T20:00:46Zcom_10324_1148com_10324_931com_10324_894col_10324_1270
Maldonado, D
Vinuesa Sanz, Guillermo
Aldana, S
Aguirre, F.L.
Cantudo, A
García García, Héctor
González, M. B.
Jiménez Molinos, Francisco
Campabadal Segura, Francesca
Miranda, E.
Dueñas Carazo, Salvador
Castán Lanaspa, María Helena
Roldán, J.B.
2023-11-14T07:54:46Z
2023-11-14T07:54:46Z
2024
Materials Science in Semiconductor Processing, 2024, vol. 169, 107878
1369-8001
https://uvadoc.uva.es/handle/10324/62918
10.1016/j.mssp.2023.107878
107878
Materials Science in Semiconductor Processing
169
The switching dynamics of TiN/Ti/HfO2/W-based resistive memories is investigated. The analysis consisted in the systematic application of voltage sweeps with different ramp rates and temperatures. The obtained results give clear insight into the role played by transient and thermal effects on the device operation. Both kinetic Monte Carlo simulations and a compact modeling approach based on the Dynamic Memdiode Model are considered in this work with the aim of assessing, in terms of their respective scopes, the nature of the physical processes that characterize the formation and rupture of the filamentary conducting channel spanning the oxide film. As a result of this study, a better understanding of the different facets of the resistive switching dynamics is achieved. It is shown that the temperature and, mainly, the applied electric field, control the switching mechanism of our devices. The Dynamic Memdiode Model, being a behavioral analytic approach, is shown to be particularly suitable for reproducing the conduction characteristics of our devices using a single set of parameters for the different operation regimes.
eng
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2023 The Authors
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
Dynamical systems
Circuits and Systems
A thorough investigation of the switching dynamics of TiN/Ti/10 nm-HfO2/W resistive memories
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/630562023-11-17T20:00:55Zcom_10324_1148com_10324_931com_10324_894col_10324_1270
Kukli, Kaupo
Aarik, Lauri
Vinuesa Sanz, Guillermo
Dueñas Carazo, Salvador
Castán Lanaspa, María Helena
García García, Héctor
Kasikov, Aarne
Ritslaid, Peeter
Piirsoo, Helle-Mai
Aarik, Jaan
2023-11-17T09:14:29Z
2023-11-17T09:14:29Z
2022
Materials, 2022, Vol. 15, Nº. 3, 877
1996-1944
https://uvadoc.uva.es/handle/10324/63056
10.3390/ma15030877
877
3
Materials
15
1996-1944
Crystal structure and electrical properties of hafnium-praseodymium oxide thin films grown by atomic layer deposition on ruthenium substrate electrodes were characterized and compared with those of undoped HfO2 films. The HfO2 reference films crystallized in the stable monoclinic phase of HfO2. Mixing HfO2 and PrOx resulted in the growth of nanocrystalline metastable tetragonal HfO2. The highest relative permittivities reaching 37–40 were measured for the films with tetragonal structures that were grown using HfO2:PrOx cycle ratio of 5:1 and possessed Pr/(Pr + Hf) atomic ratios of 0.09–0.10. All the HfO2:PrOx films exhibited resistive switching behavior. Lower commutation voltages and current values, promising in terms of reduced power consumption, were achieved for the films grown with HfO2:PrOx cycle ratios of 3:1 and 2:1 and showing Pr/(Pr + Hf) atomic ratios of 0.16–0.23. Differently from the undoped HfO2 films, the Pr-doped films showed low variability of resistance state currents and stable endurance behavior, extending over 104 switching cycles.
eng
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/4.0/
© 2022 The Authors
Atribución 4.0 Internacional
Atomic layer deposition
Crystals
Cristales - Estructura
Crystallography
Dielectrics
Dielectric properties
Electric resistors
Switching circuits
Electronics - Materials
Resistencias eléctricas
Circuitos eléctricos
Electricity
Materials science
Structure and electrical behavior of hafnium-praseodymium oxide thin films Grown by atomic layer deposition
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/648472024-01-24T08:24:44Zcom_10324_1148com_10324_931com_10324_894col_10324_1270
López-Pérez, José L.
Jaraíz Maldonado, Martín
Rubio García, José Emiliano
Enríquez Giraudo, María Lourdes
Pinacho Gómez, Ruth
Lesarri Gómez, Alberto Eugenio
2024-01-23T08:46:04Z
2024-01-23T08:46:04Z
2019
ACS Catal. 2019, 9, 6, 4804–4809
2155-5435
https://uvadoc.uva.es/handle/10324/64847
10.1021/acscatal.9b00522
4804
6
4809
ACS Catalysis
9
2155-5435
In a recent article (ACS Catal.2018, 8, 11119–11133), a comprehensive catalytic mechanism is proposed to explain the effects of residual water on the reactivity and regioselectivity of tris(pentafluorophenyl)borane catalyst in the ring-opening reaction of 1,2-epoxyoctane by 2-propanol. Using it as a representative example of a common trend followed also by other groups, we show that the heavily under-constrained (loose) kinetic modeling approach employed can lead to several pitfalls and propose an alternative, more stringent (tight) modeling protocol to avoid them. In addition to providing similar or better accuracy, this approach considerably reduces the DFT parameter calculation time (by a factor of 10 in the present case). We also show an example of how delayed or second-order mechanisms can then be added incrementally to the already built and tested, first-approximation model to achieve a highly predictive and comprehensive microkinetic model. We hope that this simple and robust microkinetic modeling protocol may contribute to the current efforts to establish new, more predictive computational methodologies for synthetic chemistry.
eng
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
Copyright © 2019 American Chemical Society. This publication is licensed under CC-BY-NC-ND.
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
An Efficient Microkinetic Modeling Protocol: Start with Only the Dominant Mechanisms, Adjust All Parameters, and Build the Complete Model Incrementally
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/648512024-01-24T08:25:56Zcom_10324_1148com_10324_931com_10324_894col_10324_1270
Thiessen, Tanner
Sidhu, Jaspreet
McIndoe, J. Scott
Rodríguez‐García, Ignacio
Rosales Martínez, Antonio
Jaraíz Maldonado, Martín
Enríquez Giraudo, María Lourdes
mcindoe
2024-01-23T09:12:05Z
2024-01-23T09:12:05Z
2022
Appl Organomet Chem.2023;37:c6979
0268-2605
https://uvadoc.uva.es/handle/10324/64851
10.1002/aoc.6979
2
Applied Organometallic Chemistry
37
1099-0739
Reduction of red bis (cyclopentadienyl)titanium (IV) dichloride (Cp2TiCl2)with manganese dust in dry THF produces a green solution that turns deepblue upon the addition of traces of water. Mass spectrometric analysis andDFT calculations have been performed to achieve a better understanding ofthe species that may be present after the interaction of water with reducedCp2TiCl2. The deep blue solution provides a handy visual indicator for thequalitative determination of water in THF
eng
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http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2022 The Authors.Applied Organometallic Chemistrypublished by John Wiley
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
Understanding the color change of the solutions of Cp2TiCl upon addition of water
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/652812024-01-30T20:01:19Zcom_10324_1148com_10324_931com_10324_894col_10324_1270
Quilez del Moral, José F.
Domingo, Victoriano
Pérez, Álvaro
Martínez Andrade, Kevin A.
López-Pérez, José Luis
Barrero, Alejandro F.
Enríquez Giraudo, María Lourdes
Jaraíz Maldonado, Martín
2024-01-30T10:19:55Z
2024-01-30T10:19:55Z
2019
J. Org. Chem. 2019, 84, 21, 13764–13779
0022-3263
https://uvadoc.uva.es/handle/10324/65281
10.1021/acs.joc.9b01996
13764
21
13779
The Journal of Organic Chemistry
84
1520-6904
We have developed and rationalized a biomimetic transformation mimicking halimane synthases based on a Lewis acid-catalyzed cascade of cyclizations and rearrangements of epoxypolyprenes. Two rings, three stereogenic centers, and a new double bond were generated in a single chemical operation. Based on this cascade transformation, we achieved a unified strategy toward the stereoselective total syntheses of halimene-type terpenoids and analogues as a proof-of-concept study. This method has been applied to the rapid synthesis of diterpene isotuberculosinol, a virulence factor of Mycobacterium tuberculosis as a representative example.
eng
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
Copyright © 2019 American Chemical Society
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
Mimicking Halimane Synthases: Monitoring a Cascade of Cyclizations and Rearrangements from Epoxypolyprenes
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/652882024-01-30T20:01:20Zcom_10324_1148com_10324_931com_10324_894col_10324_1270
Charro, Elena
Juanes San José, Marcos
Lesarri Gómez, Alberto Eugenio
Enríquez Giraudo, María Lourdes
Jaraíz Maldonado, Martín
Pinacho Gómez, Ruth
2024-01-30T10:48:34Z
2024-01-30T10:48:34Z
2018
Chem. Eur. J. 25/2018
0947-6539
https://uvadoc.uva.es/handle/10324/65288
10.1002/chem.201705727
6564
25
6571
Chemistry – A European Journal
24
1521-3765
The hydrogen bonds involving sulfur in the furfuryl mercaptan monohydrate are compared with the interactions originating from the hydroxyl group in furfuryl alcohol. The dimers with water were created in a supersonic jet expansion and characterized using microwave spectroscopy and supporting molecular orbital calculations. In furfuryl alcohol–water, a single isomer is observed, in which the water molecule forms an insertion complex with two simultaneous hydrogen bonds to the alcohol (O−H⋅⋅⋅Ow) and the ring oxygen (Ow−H⋅⋅⋅Or). When the alcohol is replaced by a thiol group in furfuryl mercaptan–water, two isomers are observed, with the thiol group preferentially behaving as proton donor to water. The first isomer is topologically equivalent to the alcohol analog but the stronger hydrogen bond is now established by water and the ring oxygen, assisted by a thiol S−H⋅⋅⋅Ow hydrogen bond. In the second isomer the sulfur group accepts a proton from water, forming a Ow−H⋅⋅⋅S hydrogen bond. Binding energies for the mercaptan–water dimer are predicted around 12 kJ mol−1 weaker than in the alcohol hydrate (B3LYP-D3(BJ)). The non-covalent interactions in the furfuryl dimers are dominantly electrostatic according to a SAPT(0) energy decomposition, but with increasing dispersion components in the mercaptan dimers, which are larger for the isomer with the weaker Ow−H⋅⋅⋅S interaction.
eng
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
Sulfur Hydrogen Bonding in Isolated Monohydrates: Furfuryl Mercaptan versus Furfuryl Alcohol
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/652912024-01-30T20:01:22Zcom_10324_1148com_10324_931com_10324_894col_10324_1270
Juanes San José, Marcos
Saragi, Rizalina Tama
Pérez, Cristóbal
Enríquez Giraudo, María Lourdes
Jaraíz Maldonado, Martín
Lesarri Gómez, Alberto Eugenio
2024-01-30T10:56:45Z
2024-01-30T10:56:45Z
2022
Phys. Chem. Chem. Phys., 2022,24, 8999-9006
1463-9076
https://uvadoc.uva.es/handle/10324/65291
10.1039/D2CP00479H
8999
15
9006
Physical Chemistry Chemical Physics
24
1463-9084
Furfuryl alcohol and thenyl alcohol contain a labile torsional chiral center, producing transiently chiral enantiomers interconverting in the nanosecond time-scale. We explored chiral molecular recognition using the weakly-bound intermolecular dimers of both alcohols, freezing stereomutation. Supersonic jet broadband microwave spectroscopy revealed homo and heterochiral diastereoisomers for each alcohol dimer and the structural characteristics of the clusters. All dimers are primarily stabilized by a moderately intense O–H⋯O hydrogen bond, but differ in the secondary interactions, which introduce additional hydrogen bonds either to the ring oxygen in furfuryl alcohol or to the π ring system in thenyl alcohol. Density-functional calculations (B2PLYP-D3(BJ)/def2-TZVP) show no clear preferences for a particular stereochemistry in the dimers, with relative energies of the order 1–2 kJ mol−1. The study suggests opportunities for the investigation of chiral recognition in molecules with torsional barriers in between transient and permanent interconversion regimes.
eng
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© the Owner Societies 2022
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
Torsional chirality and molecular recognition: the homo and heterochiral dimers of thenyl and furfuryl alcohol
info:eu-repo/semantics/article
oai:uvadoc.uva.es:10324/660092024-02-08T20:01:08Zcom_10324_1148com_10324_931com_10324_894col_10324_1270
Vinuesa Sanz, Guillermo
García García, Héctor
Poblador, Samuel
González, Mireia B
Campabadal, Francesca
Castán Lanaspa, María Helena
Dueñas Carazo, Salvador
2024-02-08T13:36:04Z
2024-02-08T13:36:04Z
2024
Materials Letters, 2024, vol. 357, 135699
0167-577X
https://uvadoc.uva.es/handle/10324/66009
10.1016/j.matlet.2023.135699
135699
Materials Letters
357
In this letter, we study the impact of the temperature on the resistive switching effect of TiN/Ti/HfO2/W metal–insulator-metal devices. An analysis of the conduction mechanisms is made, with the low resistance state being ruled by nearest neighbor hopping, while the conduction in the high resistance state is dominated by Schottky emission. Taking into account the filamentary mechanism behind the resistive switching effect, a thorough analysis of the Schottky emission allows for the calculation of the gap between conductive filament tip and metal electrode in the high resistance state. We report an increase of this gap when temperature lowers below a certain value. Moreover, the mentioned gap adopts values of integer multiples of the the mean distance between traps obtained by the hopping model.
eng
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/4.0/
© 2024 The Authors
Atribución 4.0 Internacional
Electrical engineering
Impact of the temperature on the conductive filament morphology in HfO2-based RRAM
info:eu-repo/semantics/article