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该文利用辐射强度指数衰减率,多晶半导体三碱光电阴极量子产额公式和光吸收系数公式,首次研究了多晶半导体三碱光电阴极的最佳厚度。结果表明:当I_a/I_0>0.4时,阴极最佳厚度D应在1000A以上,并且D随I_a/I_o上升而增加。高能光子产生的光电子出现在阴极内表面层。该文同时指出:对第一类阴极(S-20,S-20R,S-25),D应为300A左右;对第二类阴极(New S-25,Varo,LEP)则为900A。并预计可通过光电阴极光谱响应峰值位置设计光电阴极厚度。研究结果首次定量给出,随着光电子逸出深度和入射光波长增加,光电阴极厚度增加。如果光电子逸出深度在40～55nm之间,则对1.0μm敏感的阴极最佳厚度D应在1200A左右。
In this paper, the optimum thickness of polycrystalline semiconductor ternary photocathode was studied for the first time by using the exponential decay rate of radiation intensity, the quantum yield of polycrystalline semiconductor ternary photocathode and the formula of light absorption coefficient. The results show that when I_a / I_0> 0.4, the optimum cathode thickness D should be above 1000A, and D increases with increasing I_a / I_o. Photoelectrons generated by high-energy photons appear on the cathode inner surface layer. The paper also points out that D should be about 300A for the first type of cathodes (S-20, S-20R, S-25) and 900A for the second type of cathodes (New S-25, Varo, LEP) And it is expected that the photocathode thickness can be designed by the peak position of the photoelectric cathode spectral response. The results for the first time given quantitatively, with the photoelectron escape depth and incident light wavelength increases, the photocathode thickness increases. If the photoelectron escape depth between 40 ~ 55nm, then 1.0μm sensitive cathode optimal thickness D should be about 1200A.