Electromagnetic enhancement effect on the atomically abrupt heterojunction of Si/InAs heterostructured nanowires

Abstract

Semiconductor nanowires (NWs) present a great number of unique optical properties associated with their reduced dimension and internal structure. NWs are suitable for the fabrication of defect free Si/III-V heterostructures, allowing the combination of the properties of both Si and III-V compounds. We present here a study of the electromagnetic (EM) resonances on the atomically abrupt heterojunction (HJ) of Si/InAs axially heterostructured NWs. We studied the electromagnetic response of Si/InAs heterojunctions sensed by means of micro-Raman spectroscopy. These measurements reveal a high enhancement of the Si Raman signal when the incident laser beam is focused right on the Si/InAs interface. The experimental Raman observations are compared to simulations of finite element methods for the interaction of the focused laser beam with the heterostructured NW. The simulations explain why the enhancement is detected on the Si signal when illuminating the HJ and also provide a physical framework to understand the interaction between the incident EM field and the heterostructured NW. The understanding of this process opens the possibility of controlling the light absorption/scattering on semiconductor NWs with the use of heterostructures while taking advantage of the properties of both Si and III-V semiconductors. This is important not only for current NW based photonic nanodevices, such as light sensors, but also for the design of new optoelectronic devices based on NWs