Study of electronic band alignment in SiGeSn/GeSn quantum well via internal photoemission effect

TL;DR

This study uses internal photoemission to determine band alignment and barrier heights in SiGeSn/GeSn quantum wells, providing key insights for infrared optoelectronic device design.

Contribution

It introduces a method to accurately measure band alignment and barrier heights in SiGeSn/GeSn quantum wells using internal photoemission effect.

Findings

Effective barrier heights are approximately 22 meV for electrons and 50 meV for holes.

Identified type-I band alignment between GeSn well and SiGeSn barrier.

Internal photoemission threshold measured at 555 meV.

Abstract

SiGeSn-based optoelectronic devices, which operate across a broad infrared wavelength range, have attracted significant attention, particularly heterostructures utilizing quantum wells are widely utilized. In these structures, band alignment type and barrier height are crucial for carrier confinement, making them highly desirable information to obtain. This work leverages the internal photoemission effect to extract effective barrier heights from a Si0.024Ge0.892Sn0.084 / Ge0.882Sn0.118 single quantum well structure, which was pseudomorphically grown on Ge0.9Sn0.1 and Ge buffered Si substrate. The extracted effective barrier heights are approximately 22{plus minus}2 and 50{plus minus}2 meV for electrons and holes, respectively. Moreover, we have identified the type-I band alignment between GeSn well and SiGeSn barrier, as indicated by an internal photoemission threshold of 555 {plus minus} 1 meV.