中国光学, 2014, 7 (5): 808, 网络出版: 2014-10-23
热蒸发与离子束溅射制备LaF3薄膜的光学特性
Optical properties of LaF3 thin films prepared by thermal evaporation and ion beam sputtering
摘要
研究了钼舟热蒸发工艺和离子束溅射方法制备的单层LaF3薄膜的特性。首先,采用分光光度计测量了LaF3薄膜的透射率和反射率光谱,使用不同模型拟合得出薄膜的折射率和消光系数。然后,采用应力仪测量了加热和降温过程中LaF3薄膜的应力-温度曲线。最后,采用X射线衍射仪测试了薄膜的晶体结构。实验结果表明,热蒸发制备的LaF3(RH LaF3)存在折射率的不均匀性,在193 nm,其折射率和消光系数分别为1.687和5×10-4,而离子束溅射制备的LaF3(IBS LaF3)折射率和消光系数分别为1.714和9×10-4。 两种薄膜表现出相反的应力状态,RH LaF3薄膜具有张应力,而IBS LaF3具有压应力,退火之后其压应力减小。 热蒸发制备的MgF2/LaF3减反膜在193 nm透过率为99.4%,反射率为0.04%,离子束溅射制备的AlF3/LaF3减反膜透过率为99.2%,反射率为0.1%。
Abstract
To meet the requirements for different practical applications, we investigate the properties of single LaF3 layer deposited by resistive heating Mo-boat(RH) and ion beam sputtering(IBS) in this paper. First, transmittance and reflectance spectra of LaF3 thin films were measured by an UV-visible spectrophotometer, and the refractive indexes and extinction coefficients were obtained by using different models. Second, stress-temperature curves of LaF3 thin films during heating and cooling cycles were carried out by a stress measurement system. Finally, the X-ray diffraction(XRD) was used to characterize the microstructure of LaF3 layers. Experimental results indicate that LaF3 thin film fabricated by thermal evaporation(RH LaF3) had an inhomogeneous refractive index; the refractive index and extinction coefficient at 193 nm are 1.687 and 5×10-4 for RH LaF3, and 1.714 and 9×10-4for IBS LaF3, respectively. RH LaF3 and IBS LaF3 exhibited inverse stress status. RH LaF3 had a tensile stress and IBS LaF3 showed a compressive stress, which decreased after annealing. The transmittances are 99.4% and 99.2% for RH deposited MgF2/LaF3 AR coating and IBS deposited AlF3/LaF3 AR coating, and the corresponding measured reflectances are 0.04% and 0.1% ,respectively.
才玺坤, 张立超, 梅林, 时光. 热蒸发与离子束溅射制备LaF3薄膜的光学特性[J]. 中国光学, 2014, 7(5): 808. CAI Xi-kun, ZHANG Li-chao, MEI Lin, SHI Guang. Optical properties of LaF3 thin films prepared by thermal evaporation and ion beam sputtering[J]. Chinese Optics, 2014, 7(5): 808.