K-edge XANES of substitutional and interstitial Mn atoms in (Ga,Mn)As

TL;DR

This study combines theoretical calculations and experimental measurements to analyze the local environment of Mn atoms in (Ga,Mn)As, revealing the persistence of interstitial Mn even after annealing.

Contribution

It provides a detailed first-principles analysis of Mn K-edge XANES spectra considering both substitutional and interstitial sites in (Ga,Mn)As.

Findings

Interstitial Mn atoms remain after annealing

Quantitative analysis distinguishes impurity configurations

Theoretical spectra match experimental data

Abstract

This work reports theoretical and experimental study of the X-ray absorption near-edge structure (XANES) at the Mn K-edge in (Ga,Mn)As diluted magnetic semiconductors. The spectra have been calculated from the first-principles using FLAPW including the core-hole effect, a special attention has been paid to consequences of coexistence of Mn impurities in substitutional and tetrahedral interstitial positions. We have performed quantitative component analysis of experimental spectra collected on the (Ga,Mn)As samples before/after annealing and etching, with the aim to determine the proportion of Mn impurity configurations. Comparison of the experimental data with theoretical computations indicates that even after annealing and etching some Mn atoms still reside in interstitial sites, although the concentration of interstitial defects has been reduced by annealing.