Contributions of point defects, chemical disorder, and thermal vibrations to electronic properties of Cd(1-x)Zn(x)Te alloys

TL;DR

This study uses first principles calculations to analyze how point defects, chemical disorder, and thermal vibrations influence the electronic properties of Cd(1-x)Zn(x)Te alloys, revealing defect formation trends and dominant scattering mechanisms.

Contribution

It provides a detailed first-principles analysis of defect formation energies and electronic effects in Cd(1-x)Zn(x)Te alloys, highlighting the impact of composition and disorder.

Findings

Defect formation energies increase with Zn content, except for neutral Te vacancy.

Carrier mobilities are mainly limited by phonon scattering above 150 K.

Defect and disorder effects vary with alloy composition and strain.

Abstract

We present a first principles study based on density functional theory of thermodynamic and electronic properties of the most important intrinsic defects in the semiconductor alloy Cd(1-x)Zn(x)Te with x<0.13. The alloy is represented by a set of supercells with disorder on the Cd/Zn sublattice. Defect formation energies as well as electronic and optical transition levels are analyzed as a function of composition. We show that defect formation energies increase with Zn content with the exception of the neutral Te vacancy. This behavior is qualitatively similar to but quantitatively rather different from the effect of volumetric strain on defect properties in pure CdTe. Finally, the relative carrier scattering strengths of point defects, alloy disorder, and phonons are obtained. It is demonstrated that for realistic defect concentrations carrier mobilities are limited by phonon scattering for temperature above approximately 150 K.