真空热处理对硫化锌薄膜光学与微结构特性的影响

针对电子束蒸发离子辅助沉积的硫化锌薄膜,研究了550℃以下真空热处理对其光学与微结构特性的影响。薄膜光学和微结构特性的测试分析表明:制备后薄膜为类立方结构的ZnS,在337.5nm波长处出现临界特性转折点,随着热处理温度的增加,转折波长两侧的消光系数变化规律相反,折射率和物理厚度呈现下降趋势,薄膜的禁带宽度逐渐增加;在红外波段的薄膜折射率与热处理温度的变化并不显著,在350℃下热处理时消光系数出现转折,主要是由晶粒变小的趋势所致;通过晶相分析,硫化锌薄膜经历了类立方结构到六方结构的转换,与禁带宽度的变化趋势基本一致。分析结果表明,光学特性变化的根本原因是薄膜的微结构特性变化。

Effects of vacuum annealing on optical and microstructure properties of zinc sulfide thin film

The effect of vacuum annealing on the optical and microstructural properties of zinc sulfide (ZnS) thin films deposited by ion beam evaporation (below 550 ℃) was investigated.The analysis of optical and microstructure characteristics of the thin films show that, the microstructure of ZnS films is cubic-like structure, and has a critical characteristic turning point at a wavelength of 337.5 nm.With the increase of annealing temperature, the variation trend of the extinction coefficient on both sides of the critical wavelength is opposite.The refractive index and physical thickness decreases while the band gap of the film gradually increases.The effect of annealing temperature on the refractive index of ZnS films is slight in the near infrared, and the transition of the extinction coefficient at 350 ℃ is mainly due to the smaller tendency of the grain size.The metallographic analysis indicates that the ZnS films are transformed from cubic-like structure to hexagonal structure, which was consistent with the trend of band gap of the ZnS films.Therefore, the change of the optical properties of the thin film is lead by the microstructure variation of thin films.