Electrically active Er doping in InAs, In0.53Ga0.47As, and GaAs

Abstract

The electron concentration in dilute alloys of Er in GaAs, In0.53Ga0.47As, and InAs grown by molecular beam epitaxy is studied as a function of Er concentration and In content. Using first-principles calculations based on hybrid density functional theory, we attribute an observed increase in conduction electron concentration to Er incorporation on interstitial sites. Er also incorporates on substitutional sites where it is isovalent and electrically inactive. The formation energy of interstitial Er in InAs is significantly smaller than in GaAs, allowing for more electrically active Er in InAs. The results provide insight into characteristics of rare-earth elements as dopants in semiconductors.