Energy reversal of light- and heavy-hole excitons bound to isoelectronic centers

Abstract

Isoelectronic centers in semiconductor hosts offer convenient optical access to both heavy- and light-hole states, thus providing powerful resources for the ultrafast control of electron or hole spins. From a detailed analysis of the fine structure of excitons bound to isoelectronic defects of ${C}_{s}$ symmetry formed by two nitrogen impurities in GaAs, we demonstrate that the lowest energy states, normally exhibiting a strongly dominant heavy-hole character, can be reversed to a dominant light-hole character by the strain found in the vicinity of the emitter. This reversal suggests that strain could be used to engineer the orbital composition and ordering of excitonic states, allowing enhanced optical control over spin states.