Photoluminescence Evolution with Deposition Thickness of Ge Nanostructures Embedded in GaSb

Herein, low‐temperature and temperature‐dependent photoluminescence (PL) measurements are carried out on highly tensile‐strained Ge nanostructures embedded in GaSb matrix, and the effects of Ge deposition thickness are clarified. The direct‐gap transition‐related PL feature is successfully identified in the tensile‐strained Ge nanostructures. While typical PL thermal quenching is observed for the tensile‐strained Ge‐ and GaSb‐related transitions in the samples with a Ge deposition being thinner than the critical thickness, a negative thermal quenching shows up for the GaSb interband transition in the samples with Ge deposition surpassing the critical thickness at which high‐density nanoparticles form to relax the strain. A phenomenological thermal‐injection model is established of electrons from the tensile‐strained Ge layer to the GaSb matrix, the thermal quenching is accounted for, and a ladder‐like function of the strain‐relaxed Ge is clarified to favor the electron activation. The understanding of the effects of deposition thickness is helpful for the high‐performance Ge‐based light source for optoelectronic integration.