NEA光电阴极的表面模型

回顾了NEA光电阴极不同的表面模型，对异质结模型、偶极子模型和铯的弱核力效应进行了重点介绍。异质结模可以成功解释P型GaAs和（Cs,O）激活层之间界面势垒的存在，但这种具有体效应的异质结无法与（Cs，O）层的厚度相统一；偶极子模型认为在阴极表面形成的偶极层导致了逸出功的下降，其双偶极层模型能较好地预测和解释最佳的（Cs，O）激活层厚度，但不同的双偶极层模型对于氧在表面层存在的化学形态存在争议；铯的弱核力场效应认为铯表面层的弱核力场及氧的离化作用是界面势垒和负电子亲和势的形成原因，但它所认为的逸出功降低与基底材料无关还需进一步验证。

Surface Models for NEA Photocathode

A variety of surface models for NEA photocathode are reviewed, and heterojunction model, dipole model and cesium atomic core field effect of are specified. Heterojunction model can explain successfully for existence of interfacial barrier between the surface of P type GaAs semiconductor material and (Cs,O) activation layer, but the heterojunction with bulk characteristic is not consistent in thickness of (Cs,O) activation layer. Dipole model consider that the formation of dipole layer on the surface of photocathode lead to the decrease of escape work function, and the double dipole model makes a good estimate of optimum thickness of (Cs,O) activation layer and explains it well, but different double dipole models have disputations on the chemical composition or arragement of oxygen in the surface layer. According to the cesium atomic core field effect the formation of interfacial barrier and negative electron affinity should result from atomic core field of cesium surface layer and oxygen ionization, but the viewpoint that escape work function is independent of substrate material requires to validate further.