RT info:eu-repo/semantics/article
T1 Disorder-induced phonon self-energy of semiconductors with binary isotopic composition
A1 Widulle, F.
A1 Cardona, M.
A1 Serrano Gutiérrez, Jorge
AB Self-energy effects of Raman phonons in isotopically disordered semiconductors are deduced by perturbation theory and compared to experimental data. In contrast to the acoustic frequency region, higher-order terms contribute significantly to the self-energy at optical phonon frequencies. The asymmetric dependence of the self-energy of a binary isotope system m1−xMx on the concentration of the heavier isotope mass x can be explained by taking into account second- and third-order perturbation terms. For elemental semiconductors, the maximum of the self-energy occurs at concentrations with 0.5<x<0.7, depending on the strength of the third-order term. Reasonable approximations are imposed that allow us to derive explicit expressions for the ratio of successive perturbation terms of the real and the imaginary part of the self-energy. This basic theoretical approach is compatible with Raman spectroscopic results on diamond and silicon, with calculations based on the coherent potential approximation, and with theoretical results obtained using ab initio electronic theory. The extension of the formalism to binary compounds, by taking into account the eigenvectors at the individual sublattices, is straightforward. In this manner, we interpret recent experimental results on the disorder-induced broadening of the TO (folded) modes of SiC with a 13C-enriched carbon sublattice [S. Rohmfeld, M. Hundhausen, L. Ley, N. Schulze, and G. Pensl, Mater. Sci. Forum 338-342, 579 (2000); Phys. Rev. Lett. 86, 826 (2001)].
PB American Physical Society
SN 0163-1829
YR 2002
FD 2002
LK https://uvadoc.uva.es/handle/10324/65352
UL https://uvadoc.uva.es/handle/10324/65352
LA eng
NO Phys. Rev. B 65, 075206 (2002)
DS UVaDOC
RD 19-dic-2024