一种利用反射率理论模型指导K2CsSb光电阴极的制备方法

摘要

针对中微子和宇宙射线探测用的大尺寸K2CsSb光电阴极,本文首先利用光学导纳矩阵法,推导了适用于多层膜的K2CsSb光电阴极理论模型.通过该模型对K2CsSb光电阴极生长提出了增透层蒸镀、底K蒸镀、K/Sb同蒸、进Cs蒸镀4个阶段的制备方法,在对各个阶段的反射率变化进行的理论仿真后,发现K2CsSb厚度远低于K3Sb厚度,整个阴极结构应该为K2CsSb/K3Sb/增透层/玻璃的4层结构;仿真计算结果表明,利用该制备方法获得的K2CsSb光电阴极厚度约为40 nm.实验中,由于K与Sb同时蒸镀时采用了不同的蒸镀比例会导致截然不同的反射率曲线走势,从而影响到K2CsSb的量子效率差异.%To investigate the K2CsSb photocathode used for neutrinosor cosmic ray detection, a theoretical model of K2CsSb photocathode for multi-layer films was deduced from the optical admittance matrix method in this paper. Using this model, the four-stage preparation method for the growth of K2CsSb photocathode had been proposed, which consists of the evaporation of the transmission enhanced layer (TEL), the basic K evaporation, K/Sb co-evaporation, and Cs evaporation. From the theoretical simulation of the changes in reflectivity at each stage, we found that the thickness of K2CsSb is much less than that of K3Sb, and the entire structure should be a four-layer configuration: K2CsSb/K3Sb/TEL/glass, and the total thickness of the K2CsSb photocathode is approximately 40 nm from simulations. The experimental results show that the difference in the reflectance curves caused by the difference in the evaporation ratios between K and Sb lead to a difference in quantum efficiency.