# Band structure of strained Ge$_{1-x}$Sn$_x$ alloy: a full-zone 30-band $k\cdot p$ model

## TL;DR

This paper extends a 30-band $k ext{-}p$ model to strained Ge$_{1-x}$Sn$_x$ alloys, accurately predicting band-gap variations under different strains, aiding device optimization.

## Contribution

The paper develops and validates a comprehensive 30-band $k ext{-}p$ model for strained Ge$_{1-x}$Sn$_x$ alloys, incorporating strain effects with interpolated parameters.

## Key findings

- Model accurately predicts band-gap dependence on strain and Sn composition.
- Good agreement with experimental data validates the model.
- Provides a tool for device design optimization.

## Abstract

We extend the previous 30-band $k$$\cdot$$p$ model effectively employed for relaxed Ge$_{1-x}$Sn$_{x}$ alloy to the case of strained Ge$_{1-x}$Sn$_{x}$ alloy. The strain-relevant parameters for the 30-band $k$$\cdot$$p$ model are obtained by using linear interpolation between the values of single crystal of Ge and Sn that are from literatures and optimizations. We specially investigate the dependence of band-gap at $L$-valley and $\Gamma$-valley with different Sn composition under uniaxial and biaxial strain along [100], [110] and [111] directions. The good agreement between our theoretical predictions and experimental data validates the effectiveness of our model. Our 30-band $k$$\cdot$$p$ model and relevant input parameters successfully applied to relaxed and strained Ge$_{1-x}$Sn$_{x}$ alloy offers a powerful tool for the optimization of sophisticated devices made from such alloy.