Piezoelectricity and electronic structures of ZnO thin films: A density functional theory study

Abstract

The piezoelectric polarization of ZnO (0001) thin films is calculated for varying thickness. A new depolarization mechanism based on the occupation of quantum states induced by the internal electric field is proposed to explain the asymptotical deviation of piezoelectric polarization of thin films from the bulk value. The mechanism is also related to the stability of ZnO polar surfaces. The internal electric field is also demonstrated to have important influence on the defect electronic structures of vacancy-doped ZnO thin films.