Stimulated Raman Scattering in Ge Nanowires.

Masiar Sistani,Minh Anh Luong,Hamid Keshmiri,Maximilian G Bartmann,Martien I Den Hertog,Alois Lugstein,Rupert F Oulton,Nicholas A Güsken,Eric Robin

doi:10.1021/acs.jpcc.0c02602

Abstract

Investigating group-IV-based photonic components is a very active area of research with extensive interest in developing complementary metal-oxide-semiconductor (CMOS) compatible light sources. However, due to the indirect band gap of these materials, effective light-emitting diodes and lasers based on pure Ge or Si cannot be realized. In this context, there is considerable interest in developing group-IV based Raman lasers. Nevertheless, the low quantum yield of stimulated Raman scattering in Si and Ge requires large device footprints and high lasing thresholds. Consequently, the fabrication of integrated, energy-efficient Raman lasers is challenging. Here, we report the systematic investigation of stimulated Raman scattering (SRS) in Ge nanowires (NWs) and axial Al-Ge-Al NW heterostructures with Ge segments that come into contact with self-aligned Al leads with abrupt metal–semiconductor interfaces. Depending on their geometry, these quasi-one-dimensional (1D) heterostructures can reassemble into Ge nanowires, Ge nanodots, or Ge nanodiscs, which are monolithically integrated within monocrystalline Al (c-Al) mirrors that promote both optical confinement and effective heat dissipation. Optical mode resonances in these nanocavities support in SRS thresholds as low as 60 kW/cm2. Most notably, our findings provide a platform for elucidating the high potential of future monolithically integrated, nanoscale low-power group-IV-based Raman lasers.

Highlights

The continuing miniaturization of Si-based integrated circuits has led to high-performance compact devices with reduced power consumption at lower cost.[1−3] Associated with this rapid downscaling, metallic interconnects have become a severe bottleneck due to their high space demand, signal delays, and electromagnetic interference.[4,5] there is an increasing demand for high-speed data transmission in the optical domain.[6]
Vapor−liquid−solid[21] (VLS)-grown Ge NWs with a length of several micrometers and diameters ranging from 40 nm to 140 nm were dispersed onto a Si substrate with 100 nm of thermally grown SiO2 atop
We present a systematic experimental investigation of Raman scattering in Ge nanostructures

Summary

Introduction

The continuing miniaturization of Si-based integrated circuits has led to high-performance compact devices with reduced power consumption at lower cost.[1−3] Associated with this rapid downscaling, metallic interconnects have become a severe bottleneck due to their high space demand, signal delays, and electromagnetic interference.[4,5] there is an increasing demand for high-speed data transmission in the optical domain.[6] While effective on-chip detection and transmission have already been demonstrated,[7] conventional light-emitting diodes and lasers based on pure Si or Ge cannot be realized, due to their indirect band gap. There are only a few works on NW-based Raman lasers, including the pioneering work on cavity-enhanced SRS in GaP NWs18 and cavity-mode enhanced SRS in Si NWs.[19,20] To our knowledge, there are no further reports on this important nonlinear optical effect in semiconductor NWs

Methods

Results

Conclusion