Molecular Dynamics Studies of Dislocations in CdTe Crystals from a New Bond Order Potential

TL;DR

This study employs molecular dynamics simulations with a new bond order potential to analyze dislocation behaviors in CdTe crystals, providing insights that could improve the material's uniformity and performance in radiation detectors.

Contribution

It introduces a novel bond order potential for CdTe and applies it to systematically study dislocation configurations, energies, and mobilities in the material.

Findings

Identified 29 types of dislocations in CdTe crystals.

Developed an efficient method to calculate activation free energies.

Provided guidance for experimental dislocation control in CZT crystals.

Abstract

Cd1-xZnxTe (CZT) crystals are the leading semiconductors for radiation detection, but their application is limited by the high cost of detector-grade materials. High crystal costs primarily result from property non-uniformity that causes low manufacturing yield. While tremendous efforts have been made in the past to reduce Te inclusions / precipitates in CZT, this has not resulted in an anticipated improvement in material property uniformity. Moreover, it is recognized that in addition to Te particles, dislocation cells can also cause electric field perturbation and the associated property non-uniformity. Further improvement of the material, therefore, requires that dislocations in CZT crystals be understood and controlled. Here we use a recently developed CZT bond order potential to perform representative molecular dynamics simulations to study configurations, energies, and mobilities of 29 different types of possible dislocations in CdTe (i.e., x = 1) crystals. An efficient method to derive activation free energies and activation volumes of thermally activated dislocation motion will be explored. Our focus gives insight into understanding important dislocations in the material, and gives guidance toward experimental efforts for improving dislocation network structures in CZT crystals.