Activating Mg acceptors in AlN by oxygen: first principles calculations

TL;DR

This study uses first principles calculations to explore how oxygen influences Mg acceptors in AlN, revealing complex formation and lower activation energies that could enhance hole doping in AlN.

Contribution

The paper demonstrates that Mg and O form complexes with reduced activation energies in AlN, suggesting a new pathway for effective p-type doping without MgO precipitates.

Findings

Mg-O complexes have lower activation energies than isolated Mg in AlN.

Passive Mg-O complexes induce states that lower the activation energy.

Potential for higher hole concentration in AlN through Mg and O codoping.

Abstract

First principles calculations based on density functional theory (DFT) are performed to study the electronic properties of Mg acceptors in AlN at the presence of oxygen. It is found that Mg and O tend to form complexes like Mg-O, Mg$_2$-O, Mg$_3$-O and Mg$_4$-O which have activation energies about 0.23 eV lower than that of Mg (except of the passive Mg-O). The lower activation energies originate from the extra states over valence band top of AlN induced by the passive Mg-O. By comparing to the well-established case of GaN, it is possible to fabricate Mg and O codoped AlN without MgO precipitate. These results suggest the possibility of achieving higher hole concentration in AlN by Mg and O codoping.