AlGaAs基光电阴极光学性质计算模型分析  

Analysis of the Calculation Model for Optical Properties of AlGaAs-based Photocathodes

作　　者：赵静[1] 冯琤 覃翠[1] 郭婧[2] ZHAO Jing;FENG Cheng;QIN Cui;GUO Jing(School of Information and Communication Engineering,Nanjing Institute of Technology,Nanjing 211167,China;School of Automation,Nanjing Institute of Technology,Nanjing 211167,China)

机构地区：[1]南京工程学院信息与通信工程学院,江苏南京211167 [2]南京工程学院自动化学院,江苏南京211167

出　　处：《南京工程学院学报（自然科学版）》2023年第3期14-20,共7页Journal of Nanjing Institute of Technology(Natural Science Edition)

基　　金：国家自然科学基金项目(62001214);江苏省自然科学基金项目(BK20191012)。

摘　　要：为了分析不同波长响应对光电阴极结构的要求,提出适用于各类响应的AlGaAs基光电阴极的计算模型.通过宽光谱响应GaAs和窄带响应AlGaAs基光电阴极样品试验证实模型的有效性.基于该模型仿真研究AlGaAs基光电阴极组件中GaAs发射层及各子层、AlGaAs窗口层、Si_(3)N_(4)增透层的厚度与400~900 nm单波长光子吸收情况的分布关系.仿真结果表明,同一波长响应下,GaAs发射层对光电阴极吸收率的影响最大,其次是Si_(3)N_(4)增透层,而AlGaAs窗口层对吸收率的影响不明显.要得到90%以上的吸收率,在600 nm波长响应下GaAs发射层厚度应大于0.5μm,700 nm波长响应下GaAs发射层厚度应大于0.8μm,800 nm波长响应下GaAs发射层厚度应大于1.5μm.400~600 nm波段的光子主要在GaAs发射层表面0.2μm内被吸收,700~800 nm波段的光子主要在GaAs发射层表面0.6μm内被吸收,而850 nm以后的光子在各子层间的吸收比较均匀.该结论对不同响应AlGaAs基光电阴极的优化设计具有一定的参考价值.To analyze the requirements on photocathodes structures for dfferent wavelength responses,a calculation model of AlGaAs-based photocathodes applicable to various responses is proposed is proposed.The model's validity is verified through experimental results obtained from a wide-spectrum response GaAs photocathode sample and AlGaAs photocathode sample with narrow-band response.Additionally,utilizing this model,the distribution relationships were simulated within the AlGaAs-based photocathode module regarding the thickness of GaAs emission layer,each sub-layer,the AlGaAs window layer,the Si_(3)N_(4)anti-reflection layer,and the absorption of single-wavelength photons within the 400 and 900 nm wavelength range.The results demonstrate that,under identical wavelength response coniditions,the GaAs emission layer significantly influences the photocathode's absorption rate,followed by the Si,N4 antireflection layer,while the AlGaAs window layer's thickness exhibits no notable impact on the absorption rate.To achieve an absorptivity of more than 90%,the thickness of GaAs emission layer should exceed 0.5μm at 600 nm,0.8μm at 700 nm,and 1.5μm at 800 nm.The photons at 400~600 nm wavelength are mainly absorbed within 0.2μm of the surface of the emission layer,and the photons at 700~800 nm wavelength are mainly absorbed within 0.6μm of the surface of the emission layer,while the photons after 850 nm are absorbed evenly among each of the sub-layers.The conclusions offer valuable guidance for optimizing the design of AlGaAs-based photocathodes under varying wavelength responses.

关 键 词：AlGaAs基光电阴极 多发射层模型 吸收率 阴极厚度 单波长 

分 类 号：O462.3[理学—电子物理学]