It was recalled that the preparation of high-quality reproducible p-type ZnO was proving difficult because of the strong self-compensation effect of intrinsic defects. Here, one of the native defects, the O vacancy, was explicitly investigated by means of theoretical and experimental studies. It was predicted that O vacancy was a deep

donor in ZnO. It was suggested that the O vacancy should be suppressed in p-type ZnO. In the experimental study of P-doped ZnO, the role of O partial pressure in the fabrication of p-type ZnO was further explored by using radio-frequency sputtering. It was also found that the conduction type for P-doped ZnO thin films could be controlled by adjusting the O partial pressure. It was demonstrated that p-type conduction could be stabilized in a narrow O partial pressure window.

Theoretical and Experimental Studies on Oxygen Vacancy in p-Type ZnO. Z.Q.Hu, P.Wu, H.Wong: Physica B, 2007, 401-402, 417-20