Enhancement of TC by a carrier codoping method with size compensation for nitride-based ferromagnetic dilutemagnetic semiconductors

Abstract

Based on ab initio calculations of electronic structures of Mn-doped GaN, a carriercodoping method with size compensation to enhance the Curie temperature(TC) of GaN-based dilute magnetic semiconductors is proposed. Beryllium (Be) is chosen asa codopant to reduce the volume expansion caused by Mn doping, and also toenhance the 3d-density of states at Fermi level by hole doping. It is found that themid-gap impurity band is strongly broadened due to strong p–d hybridization,resulting in a considerable increase of the hole density. With Be substituting boththe cations and anions, the reduction of the antiferromagnetic super-exchangeinteraction in the regime of high Mn-concentrations and the highest value ofTC due to the ferromagnetic double exchange interaction are strongly expected.