氮气中退火对ZnO薄膜结构与光学性能的影响

Effect of Annealing in N_2 on Structure and Optical Properties of ZnO Thin Films

采用直流磁控溅射法制备了ZnO薄膜,并将样品在氮气中进行了退火。对样品的表面形貌、结构性能、发光特性、透射光谱分别进行了检测。结果表明:退火后,样品的结晶质量提高,光致发光峰增强,在可见光范围内的平均透过率也有所增加。计算表明:退火后ZnO薄膜的禁带宽度略有减小。这可能是氮掺入ZnO薄膜后,N2p与O2p形成杂化轨道,二者能带部分重叠,从而使价带变宽、禁带变窄。

ZnO thin films were prepared by DC reactive magnetron sputtering and then annealed in N2. The characteristics of its surface morphology, microstructures,luminescence, and transmission spectrum were studied respectively. The effect of annealing in N2 on the structure and optical properties of ZnO thin films was studied. The experimental results show that after annealing,the quality of ZnO thin films is enhanced obviously,the intensity of PL and the average transmission in visible light increase as well. It is found that the band gap of ZnO thin films becomes narrow to a certain extent. It might be ZnO doped nitrogen and forms N2p and O2p hybrid orbits. These hybrid ones overlap partly in energy levels, which leads to wider valence band and narrower band gap.