Energetics of native defects in CuAlO2

Delafossite CuAlO2 is a prototype p-type transparent conducting oxide. We have performed ab initio total energy calculation oil native point defects to investigate the origin of p-type conductivity in 'undoped' CuAlO2. Copper- and oxygen-related defects, such as vacancies, interstitials, and antisites in their relevant charge states are considered. We have found that oxygen interstitial and copper vacancy have relatively low formation energies and they are the relevant defects in CuAlO2. It is also found that oxygen interstitial induces deep levels, while copper vacancy induce no deep levels in the band gap. Our results indicate that copper vacancy plays an important role in the p-type conductivity and also controlling of copper and oxygen pressure is decisively important for the fabrication of CuAlO2. (c) 2006 Elsevier B.V. All rights reserved.