Effects of n-type doping on active Fe sites in ion implanted Fe in InP

An n-type doping significantly increases the number of active Fe atoms substituting In (Fe-In) in Fe-implanted InP. We address the origin of this doping effect by investigating the relative stability of neutral and charged Fe-In states with first-principles theoretical methods. The present results show that donor-acceptor pairs have direct stabilizing effects on Fe-In related to charge rearrangements strongly localized at the Fe site and involving d orbitals. The resulting microscopic description of the doping effects accounts for the experimental findings and provides a significant guideline for tuning electronic and optical properties of Fe implanted InP and InP-based compounds.