Generalized band anti-crossing model for highly mismatched semiconductors applied to BeSe$_{x}$Te$_{1 - x}$

TL;DR

This paper introduces a generalized band anti-crossing model based on the Anderson impurity Hamiltonian, formulated within empirical tight-binding theory, to accurately describe the electronic properties of highly mismatched semiconductor alloys like BeSe$_{x}$Te$_{1-x}$.

Contribution

The paper develops a parameter-efficient, generalized BAC model applicable to highly mismatched semiconductors, extending previous models and validated on BeSe$_{x}$Te$_{1-x}$ alloys.

Findings

Large band bowing observed, especially on Se-rich side.

Model successfully predicts electronic and optical properties.

Linear interpolation used for arbitrary compositions.

Abstract

We report a new model for highly mismatched semiconductor (HMS) alloys. Based on the Anderson impurity Hamiltonian, the model generalizes the recent band anti-crossing (BAC) model, which successfully explains the band bowing in highly mismatched semiconductors. Our model is formulated in empirical tight-binding (ETB) theory and uses the so called sp$^{3}$s* parameterization. It does not need extra parameters other than bulk ones. The model has been applied to BeSe$_{x}$Te$_{1 - x}$ alloy. BeTe and BeSe are wide-band gap and highly mismatched semiconductors. Calculations show large band bowing, larger on the Se rich side than on the Te rich side. Linear interpolation is used for an arbitrary concentration $x$. The results are applied to calculation of electronic and optical properties of BeSe$_{0.41}$Te$_{0.59}$ lattice matched to Si in a superlattice configuration.