%0 Journal Article
%T Comparison between gradient-doping and uniform-doping GaN photocathodes<br>梯度掺杂与均匀掺杂GaN光电阴极的对比研究
%A Wang Xiao-Hui
%A Chang Ben-Kang
%A Qian Yun-Sheng
%A Gao Pin
%A Zhang Yi-Jun
%A Guo Xiang-Yang
%A Du Xiao-Qing
%A <br>王晓晖
%A 常本康
%A 钱芸生
%A 高频
%A 张益军
%A 郭向阳
%A 杜晓晴
%J 物理学报
%D 2011
%I 
%X In order to enhance the quantum efficiencies of negative electron affinity (NEA) GaN photocathodes, gradient-doping reflection-mode GaN photocathodes are grown by metal organic chemical vapor deposition (MOCVD)at doping concentrations of 1×1018cm-3, 4×1017cm-3, 2×1017cm-3 and 6×1016cm-3 from the body to the surface, with the thickness of each doping region being about 45nm and the total thickness of GaN 180 nm. The gradient-doping GaN photocathodes are activated in an ultra-high vacuum system and are compared with two kinds of uniform-doping GaN photocathodes whose thicknesses are both 150 nm and doping concentrations are 1.6×1017cm-3 and 3×1018cm-3 separately. The results show that both the photocurrent growth rate and the maximum photocurrent of the gradient-doping GaN photocathodes are greater than those of the uniform-doping GaN in the Cs/O activation process, and the multi-test system measured maximum quantum efficiency of the gradient-doping NEA GaN photocathode is about 56% which is as high as the double of the uniform-doping. Calculations show that the energy band bendings of the gradient-doping GaN photocathodes are 0.024eV, 0.018eV and 0.031eV from the body to the surface, a larger electron drift and diffusion length are gained due to the built-in electric field formed by the energy band bending, because of the 0.073eV total energy band bending the photoelectrons reaching the surface have higher energies and pass through the surface barrier more easily. Therefore the gradient-doping NEA GaN photocathodes have greater quantum efficiencies.
%K NEA GaN photocathodes
%K gradient-doping
%K quantum efficiency
%K energy band structure<br>NEAGaN光电阴极
%K 梯度掺杂
%K 量子效率
%K 能带结构
%U http://www.alljournals.cn/get_abstract_url.aspx?pcid=6E709DC38FA1D09A4B578DD0906875B5B44D4D294832BB8E&cid=47EA7CFDDEBB28E0&jid=29DF2CB55EF687E7EFA80DFD4B978260&aid=072527642A61DC20ECF328E0B3C60BEE&yid=9377ED8094509821&vid=BFE7933E5EEA150D&iid=E158A972A605785F&sid=EB8E83807F36F05B&eid=2A92ABD90588B251&journal_id=1000-3290&journal_name=物理学报&referenced_num=0&reference_num=13