Evolution of surface potential barrier for negative-electron-affinity GaAs photocathodes
Evolution of surface potential barrier for negative-electron-affinity GaAs photocathodes
复制标题
DOI：
10.1063/1.3063686
复制
发表时间：
2009-01
影响因子：
3.2
通讯作者：
J. Zou;Benkang Chang;Zhi Yang;Yijun Zhang;J. Qiao
中科院分区：
文献类型：
--
作者：
J. Zou;Benkang Chang;Zhi Yang;Yijun Zhang;J. Qiao
通过在室温下使用光谱响应和角度相关的 X 射线光电子能谱 (ADXPS) 测量，研究了超高真空系统中反射模式 GaAs 光电阴极表面势垒的演变。发射到真空中的电子的逃逸概率是作为入射电子能量、表面势垒高度和厚度的函数而获得的。基于新的逃逸概率表达式，我们利用量子效率方程通过拟合光谱响应曲线获得了反射模式负电子亲和力（NEA）阴极的表面势垒参数。这些参数揭示了 NEA 阴极表面在降解过程中的演变。此外，新激活的和降解的阴极的表面层结构都是根据 ADXPS 谱计算的。计算结果与拟合的障碍参数相当一致。
The evolution of surface potential barrier for reflection-mode GaAs photocathodes in an ultrahigh vacuum system has been investigated by using spectral response and angle-dependent x-ray photoelectron spectroscopy (ADXPS) measurements at room temperature. The escape probabilities of electrons emitted into vacuum are obtained as a function of the incident electron energy, surface barrier height, and thickness. Based on the new escape probability expressions, we obtain the surface barrier parameters of the reflection-mode negative-electron-affinity (NEA) cathodes from the fit of the spectral response curves by using quantum-efficiency equations. These parameters reveal the evolution of the NEA cathode surface during the degradation process. In addition, the surface layer structure of both the freshly activated and degraded cathodes is calculated from the ADXPS spectra. The calculated results are in fair agreement with the fitted barrier parameters.