Excitation power-independent photoluminescence of inverted quantum hut structures embedded in SiGe superlattice

Abstract

Optical properties of semiconductor nanostructures can be quite different from the bulk semiconductors. We present here results of a photoluminescence study of MBE-grown SiGe superlattice structures having inverted quantum huts of Ge formed below Ge-on-Si interfaces. As these structures form by continuous alloying with the lower Si layers, the interfacial strain is greatly reduced, leading to a band-alignment, which is different from that obtained for conventional quantum dots formed above Ge-on-Si interfaces. Thus, unlike conventional Ge quantum dots, the presented quantum structures exhibit excitation power-independent photoluminescence emission. Temperature dependence of photoluminescence energy follows typical relation expected in a semiconductor, but at higher temperature when dominating contribution comes from the tip of the quantum hut, change in the photoluminescence energy becomes weakly dependent on temperature. These results may be influential in the development of silicon-based optical materials.