Dopant-Dopant Interactions in Beryllium doped Indium Gallium Arsenide: an Ab Initio Study

TL;DR

This study uses ab initio calculations to analyze dopant interactions in beryllium-doped InGaAs, highlighting the importance of interstitial defects and their interactions for accurate modeling.

Contribution

It provides new insights into dopant-defect interactions, especially the significance of interstitials, and suggests treating In and Ga separately in models.

Findings

Interstitial Be stabilizes significantly with substitutionals.

Ga interstitials are stabilized by Be interstitials.

Metastable Be-Be-Ga complexes can form with 0.26 eV dissociation energy.

Abstract

We present an ab initio study of dopant-dopant interactions in beryllium-doped InGaAs. We consider defect formation energies of various interstitial and substitutional defects and their combinations. We find that all substitutional-substitutional interactions can be neglected. On the other hand, interactions involving an interstitial defect are significant. Specially, interstitial Be is stabilized by about 0.9/1.0 eV in the presence of one/two BeGa substitutionals. Ga interstitial is also substantially stabilized by Be interstitials. Two Be interstitials can form a metastable Be-Be-Ga complex with a dissociation energy of 0.26 eV/Be. Therefore, interstitial defects and defect-defect interactions should be considered in accurate models of Be doped InGaAs. We suggest that In and Ga should be treated as separate atoms and not lumped into a single effective group III element, as has been done before. We identified dopant-centred states which indicate the presence of other charge states at finite temperatures, specifically, the presence of Beint+1 (as opposed to Beint+2 at 0K).