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

SiGeSn-based optoelectronic devices, which operate across a broad infrared wavelength range, have garnered significant attention. Among these, heterostructures incorporating quantum wells are particularly promising due to their enhanced carrier confinement. In such structures, the type of band alignment and the associated barrier heights are critical parameters, directly influencing device performance. In this work, we employ internal photoemission measurements to extract the effective barrier heights in a Si_0.024Ge_0.892Sn_0.084/Ge_0.882Sn_0.118 single quantum well, which is pseudomorphically grown on a Ge_0.9Sn_0.1 buffer atop a Ge buffered Si substrate. The extracted effective barrier heights are approximately 22 ± 2 meV for electrons and 50 ± 2 meV for holes. Additionally, based on the IPE threshold energy of 555 ± 1 meV, we have experimentally identified a type-I band alignment between the GeSn well and SiGeSn barrier layers—an important finding for the design of efficient infrared photonic devices.