均匀掺杂和梯度掺杂结构GaN光电阴极性能对比研究  

Comparative Study of Uniform-Doping and Gradient-Doping Negative Electron Affinity GaN Photocathodes

作　　者：李飙[1] 常本康[1] 徐源[1] 杜晓晴[2] 杜玉杰[1] 付小倩[1] 王晓晖[1] 张俊举[1] 

机构地区：[1]南京理工大学电子工程与光电技术学院,江苏南京210094 [2]重庆大学光电工程学院,重庆400030

出　　处：《光谱学与光谱分析》2011年第8期2036-2039,共4页Spectroscopy and Spectral Analysis

基　　金：国家自然科学基金项目(60871012;60701013);南京理工大学自主科研专项计划项目(2010ZYTS032)资助

摘　　要：高温退火与Cs/O激活是形成负电子亲和势GaN光电阴极的外来诱因,GaN材料本身性能是影响阴极形成的内在因素。针对均匀掺杂和梯度掺杂GaN光电阴极在结构上的不同,结合阴极在激活过程中光电流的变化规律和激活后的量子产额,分析了均匀掺杂和梯度掺杂负电子亲和势GaN光电阴极性能的异同。实验表明,与均匀掺杂结构阴极相比,梯度掺杂结构阴极在激活过程中光电流增速较慢,激活时间相对较长,激活成功后量子效率较高。采用场助光电阴极发射模型可以很好地解释二者间存在的差异,梯度掺杂结构中内建电场的存在增加了电子向阴极表面的漂移运动,提高了电子到达阴极表面的几率。High temperature annealing and Cs/O activation are external incentives,while the property of GaN material is internal factor in the preparation of negative electron affinity GaN photocathode.The similarities and differences of the performance of the two structure photocathodes are analysed based on the difference of the structure between uniform-doping and gradient-doping negative electron affinity GaN photocathodes and the changes in photocurrents in activation and the quantum yield after successfully activated of GaN photocathodes.Experiments show that： the photocurrent growth rate is slower in activation,activation time is longer and quantum efficiency is higher after successfully activated of gradient-doping GaN photocathode than those of uniform-doping photocathode respectively.The field-assisted photocathode emission model can explain the differences between the two,built-in electric field of gradient-doping structure creates additional electronic drift to the photocathode surface,and the probability of electrons to reach the photocathode surface is improved correspondingly.

关 键 词：负电子亲和势 氮化镓 均匀掺杂 梯度掺杂 光电阴极 场助 量子效率 

分 类 号：TN204[电子电信—物理电子学]