多碱光电阴极灵敏度理论模拟  

Simulation of Multi-Alkali Photocathode Sensitivity

作　　者：安迎波 徐向晏[1] 孙巧霞[1,2] 曹希斌[1] 温文龙[1] 王俊锋[1] 刘虎林[1] 卢裕[1] 田进寿[1] 李晓峰 李燕红 

机构地区：[1]中国科学院西安光学精密机械研究所瞬态光学与光子技术国家重点实验室,陕西西安710119 [2]中国科学院大学,北京100049 [3]微光夜视技术重点实验室,陕西西安710059

出　　处：《光学学报》2014年第3期325-330,共6页Acta Optica Sinica

基　　金：国家自然科学基金(11274377)

摘　　要：针对多碱光电阴极进行了理论建模和性能模拟,采用层状模型:Na2KSb+K2CsSb+Sb·Cs偶极层,讨论了各层厚度、掺杂离子浓度对多碱阴极能带以及光谱响应特性的影响,结果显示表面K2CsSb和Sb·Cs两层的n型掺杂较高时,能够有效降低表面亲和势,有利于光电子的输运以及逸出。Na2KSb的掺杂离子浓度并非越高越好,主要原因是掺杂离子浓度影响着内建电场强度与范围,内建电场增大使电子扩散距离增加,有更高的几率到达阴极表面,在掺杂离子浓度为1016 cm-3左右时可获得最高灵敏度。分析了厚度对阴极灵敏度的影响,对于特定波长入射光,存在最佳厚度使对应波长的灵敏度最高,且由于内建电场的影响,不同掺杂离子浓度会使最佳厚度有所不同,当内建电场较强时,阴极的最佳厚度增大。对700nm入射光,在掺杂离子浓度为1017 cm-3以及1016 cm-3时,最佳厚度分别为80nm和200nm。Modeling and simulation of multi-alkali photocathode have been studied. The stucture of photocathode is employed with layered model： Na2KSb ＋ K2CsSb ＋ Sb·Cs dipole layer. Effects of the thickness and doping concentration of each layer on the energy band and spectral response character have been discussed. The result shows that when the N-doping concentration in the K2 CsSb and Sb· Cs layers is heavier, it can effectively lower the electron affinity, which will be helpful to the transport and escape of the photoelectron. The doping concentration of Na2 KSb is not that the higher the better, which comes from the effect of doping concentration on build-in electric field intensity and range. The diffuse distance of electron will get further when under higher build-in electric field intensity, which can make electron have higher probability to reach the surface of photocathode. The highest sensitivity is got when doping concentration is about 10^16 cm^-3. Influence of thickness on sensitivity is analysed, for a certain wavelength incident light, there exists the optimum thickness. Under the impact of the build-in electric field, different doping concentrations have the corresponding thickness. With higher build-in electric field, the optimum thickness enhanced, meanwhile. For 700 nm incident light, when doping concentration is 10^17 cm^-3 or10^16 cm^-3 , the optimum thickness is 80 nm or 200 nm, respectively.

关 键 词：光电子学 多碱光电阴极 掺杂离子浓度 灵敏度 电子扩散距离 

分 类 号：O462.3[理学—电子物理学]