热舟蒸发LaF3薄膜的紫外性能研究

The study of ultraviolet properties of resistant-boat evaporated LaF_3 films

研究了沉积温度对热舟蒸发氟化镧薄膜结构和光学性能的影响,沉积温度从200℃上升到350℃,间隔为50℃.采用分光光度计测量了样品的透射率和反射率光谱曲线,并在此基础上进行了光学损耗、光学常数以及带隙和截止波长的计算.采用表面轮廓仪进行了表面形貌和表面粗糙度的标定,采用X射线衍射(XRD)方法测量了不同沉积温度下样品的微结构.发现在短波长波段,随着沉积温度的升高,光学损耗增加,晶粒尺寸增大,表面粗糙度略有增加.不过散射损耗在光学损耗中所占比例均很小,光学损耗的增加主要由吸收损耗引起.随着沉积温度的升高,折射率与消光系数增大,带隙变小,相对应的截止波长向长波方向移动.

The effects of depositing temperature on structure and optical properties of resistant-boat evaporated LaF3 single layers were investigated, The films were produced at different temperatures from 200℃ to 350℃ by increasing step of 50℃. The optical loss, optical constants, optical band gap and cut-off wavelength were deduced on the basis of the transmittance and reflectance curves. Profile and surface roughness measurement instrument was used to determine the rms surface roughness. Microstructure of the samples was characterized by X-ray diffraction （XRD） . It was found that the total optical loss, the grain size and the rms surface roughness increased with the increasing of the depositing temperature at the short wavelength period. And the increasing total optical loss with depositing temperature was attributed to the absorption because the scattering occupied the very low percent in the whole loss. The samples deposited at higher temperature had the higher refractive index and extinction coefficient and lower optical band gap. The cut-off wavelength shifted to the long wavelength as the depoaiting temperature increased.