Possible approach to fabricate p-type ZnO through the Be-N codoping method: First-principles calculations

An ab initio calculation based on density functional theory is applied to study Be-N codoped ZnO and the possible complexes are discussed. The calculated results show that the substitutional N defect at the O site (N-O) easily binds with the interstitial Be (Be-i), rather than the substitutional Be defect at the Zn site (Be-Zn). This indicates that 4Be(Zn)-N-O complex is not a stable acceptor and is unlikely to form. Fortunately, Be-i-3N(O) is of high structural stability and its transition energy is very low due to the impurity band caused by the Be-i-2N(O) passive complex. Therefore, Be-i-3N(O) can serve as a stable source of p-type conductivity. In addition, it is also suggested that Be-N codoped p-type ZnO can be prepared under Zn-rich condition because Be-i-3N(O) has the lowest formation energy in this environment. (C) 2011 Elsevier Ltd. All rights reserved.