Enhancing hole concentration in AlN by Mg:O codoping:: Ab initio study

Ab initio study based on density functional theory is performed to study the binding energies of Mg acceptors to single oxygen in AlN and the activation energies of the resultant Mg-n-O complexes (n=2, 3, and 4). It is found that such complexes are energetically favored and have activation energies at least 0.23 eV lower than that of single Mg. The lower activation energies originate from the extra states over the 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:O codoped AlN without MgO precipitates. These results suggest the possibility of achieving higher hole concentration in AlN by Mg:O codoping.