实验分别采用5种不同的沉积速率(0.44,0.30,0.18,0.08和0.04 nm/s)制备了金属银薄膜,膜系结构为基底/Al₂O₃/Ag/Al₂O₃/Air。光谱测试结果表明,沉积速率0.18 nm/s的样品具有最高的平均反射率。采用X射线衍射(XRD)仪分析了5个样品的X射线衍射谱。银膜择优取向(111)晶向,0.18 nm/s的样品衍射峰强度最大、衍射峰半峰全宽最小、晶粒尺寸最大,说明此沉积速率下结晶程度最高。过快或者过慢的沉积速率会导致银膜结晶程度下降,从而导致平均消光系数增大和反射率下降。在实验条件下,银膜的最佳沉积速率在0.18 nm/s附近,此时制备的银膜具备最好的结晶程度和最高的反射率,此结论不同于传统意义上认为热蒸发银膜速率越快,成膜质量越高、光谱特性越好的观点。

Silver films bedded and covered Al₂O₃ were prepared with five different deposition rates:0.44,0.30,0.18,0.08 and 0.04 nm/s. The reflectance spectra indicated the sample with a deposition rate of 0.18 nm/s had the highest average reflectance. X-ray diffraction (XRD) spectra of the five samples were obtained by XRD,which showed silver (111) was the preferred orientation. The sample with the deposition rate of 0.18 nm/s had the highest intensity of diffraction peak,the narrowest full width at half maximum (FWHM) and the biggest average grain size,which totally meant the sample had a best crystallinity. Samples with faster or slower deposition rate would cause low level crystallinity and resulted in the increase of extinction coefficient and decrease of reflectance. In our experimental conditions,it is suggested the best deposition rate is around 0.18 nm/s,which can lead to the best crystallinity and average reflectance. The result is different from the opinion which originally regarded the quality and reflectance of silver films would be better with faster thermal evaporation deposition rate.