Intrinsic defects, including vacancies at the Cu and Al sites (VCu and VAl), substitutional Cu at the Al site (CuAl), and interstitial O (Oi), have been proposed to be responsible for the p-type conductivity in CuAlO2. We have investigated the formation energies of these and other intrinsic defects in CuAlO2 using GGA+U calculations. Our results support previous studies that the potential alignment and image charge correction are required in the calculation of defect formation energies by using the supercell approach. In CuAlO2, these p-type defects (VCu, VAl, CuAl, and Oi) invariably have lower formation energies than their n-type counterparts. Particularly, VCu and CuAl have the lowest formation energies among intrinsic defects, and therefore are most likely responsible for the p-type conductivity. However, the transition levels of the VCu and CuAl defects are deep, which are responsible for the poor p-type conductivity in CuAlO2.
Intrinsic Defects in LiMn2O4: First-Principles Calculations