Lattice constant in diluted magnetic semiconductors (Ga,Mn)As

TL;DR

This study uses density-functional calculations to analyze how native defects and Mn concentration affect the lattice constant in (Ga,Mn)As, revealing that defects and compensation levels influence lattice expansion.

Contribution

It provides a quantitative analysis of the compositional dependence of lattice constants in (Ga,Mn)As considering native defects and Mn positioning.

Findings

Lattice constant is relatively unaffected by Mn concentration in perfect crystals.

Interstitial Mn and As antisite defects increase the lattice constant.

Materials with low compensation have lattice constants close to pure GaAs.

Abstract

We use the density-functional calculations to investigate the compositional dependence of the lattice constant of (Ga,Mn)As containing various native defects. The lattice constant of perfect mixed crystals does not depend much on the concentration of Mn. The lattice parameter increases if some Mn atoms occupy interstitial positions. The same happens if As antisite defects are present. A quantitative agreement with the observed compositional dependence is obtained for materials close to a complete compensation due to these two donors. The increase of the lattice constant of (Ga,Mn)As is correlated with the degree of compensation: the materials with low compensation should have lattice constants close to the lattice constant of GaAs crystal.