退火对Si(111)衬底上ZnO薄膜的结构和发光特性的影响

Effects of Annealing on the Structure and Photoluminescence of ZnO Thin Films Grown on Silicon Substrate

采用磁控溅射法在硅(111)衬底上制备了C轴高度取向的ZnO薄膜,并研究了退火温度和氧气气氛对ZnO薄膜晶体质量、晶粒度大小和光致发光谱的影响。X射线衍射表明,所有薄膜均为高度C轴择优取向,当退火温度低于900℃时,随着退火温度的升高,薄膜的取向性和结晶度都明显提高。室温下对ZnO薄膜进行了光谱分析,退火后的样品均可观测到明显的紫光发射。在一定的退火温度范围内,还可以观测到明显的紫外双峰。空气中退火的样品,当退火温度达到或高于600℃还可观测到绿光发射。实验结果表明,发光峰强度随退火温度和氧气气氛不同而不同,通过改变退火时的温度和氧气气氛可以改变ZnO薄膜的微结构和发光性质。

ZnO thin films were grown by magnetron sputtering technique on Si （ 111 ） substrates, some of those films were annealed at different temperatures from 300℃ to 600℃ in vacuum and the others were annealed at different temperatures from 300℃ to 900℃ in the air. The influences of annealing temperature and condition on the quality, grain size and photoluminescence of ZnO films are discussed in this article. X-ray diffraction patterns indicated that the films were C-axis oriented. When the annealing temperature was lower than 900℃, the grain size increased with the increase of annealing temperature. The emission spectra excitated by 325nm were measured at room temperature, and a 380nm emission was observed when the annealing temperature was lower than 400℃. Two ultraviolet luminescence peaks were observed when the annealing temperature was from 400℃ to 600℃. When the annealing temperature was the same as or high than 600℃, a 380nm emission and a 530nm emission were observed. These results indicate that ZnO thin films by magnetron sputtering on the silicon substrates are high quality films. At the same time, the crystal quality and optical properties of ZnO thin films can be improved through changing annealing temperature and condition.