Investigation on the Electronic Structure and Optical Properties of ZnO Nanofilms

Abstract

The electronic structure and optical properties of wurtzite ZnO nanofilms with different thickness are investigated systematically by using the first-principles approach. The results indicate that the valence band properties of the ZnO nanofilms are mainly determined by the Zn: 3d state and O: 2p state. And its conduction band properties are determined by Zn: 4s state and Zn: 4p state. The band gap decreases with the thickness of nanofilms increasing in [0001] direction. It is also found that the interband transition absorption edge of ZnO nanofilms decreasing from 5.5 eV to 2.7 eV with the thickness of nanofilms increasing from single layer to five layers. The interband transition of reflection spectrum occurs mainly in the range of 10 eV to 18 eV, which is in line with the ionic bonding characteristic of wurtzite ZnO.