Auger-mediated radiative recombination in three-dimensional silicon/silicon-germanium nanostructures

TL;DR

This paper demonstrates that Auger-mediated radiative recombination in 3D silicon/silicon-germanium nanostructures enables nearly temperature-independent light emission with fast radiative lifetimes, contrasting bulk silicon behavior.

Contribution

It reveals a novel Auger-assisted radiative process in Si/SiGe nanostructures that produces efficient, nearly temperature-independent luminescence, unlike traditional silicon.

Findings

EHP/EHD formation in Si/SiGe nanostructures

Near temperature-independent luminescence in nanometer-thick Si layers

Radiative lifetime approaching 10^-8 seconds

Abstract

In a semiconductor heterostructure with type II energy band alignment, the spatial separation between electrons and holes slows down their radiative recombination. With increasing excitation intensity, Auger recombination quickly becomes the dominate recombination channel, and it produces carrier ejection from the quantum well. Here, we show that in Si/SiGe three-dimensional nanostructures, this efficient process facilitates the formation of an electron-hole plasma (EHP) and/or electron-hole droplets (EHDs) in thin Si barriers separating SiGe clusters. In contrast to conventional, strongly temperature dependent and slow radiative carrier recombination in bulk Si, this EHD/EHP luminescence in nanometer-thick Si layers is found to be nearly temperature independent with radiative lifetime approaching 10^-8 s, which is only slightly slower than that found in direct band gap III-V semiconductors.