Experimental Calibration of Sn‐Related Varshni Parameters for High Sn Content GeSn Layers

From temperature‐dependent photoluminescence of a single Ge_0.84Sn_0.16 sample, Sn‐related Varshni parameters are extracted and used as input parameters in an 8‐band k·p model, and predict direct bandgap energies of high Sn content GeSn alloys with concentration varying from 8% to 16%. Then, exhaustively compared are the calculated direct Γ‐valley bandgap energies to photoluminescence results of 13% and 16% Sn content alloys and to direct bandgap energies found in literature. The agreement between k·p modeling and experimental datasets is close to 3% for different strain conditions of GeSn epilayers. The outcome of this study is an 8‐band k·p model with a fixed set of parameters, the model being self‐sufficient to describe the direct bandgap of Ge_1?xSn_x layers with x varying from 8% to 16% for large ranges of strain and temperature.