Li Biao, Chang Ben-Kang, Xu Yuan, Du Xiao-Qing, Du Yu-Jie, Fu Xiao-Qian, Wang Xiao-Hui, Zhang Jun-Ju
Institute of Electronic Engineering and Optoelectronic Technology, Nanjing University of Science and Technology, Nanjing 210094, China.
Guang Pu Xue Yu Guang Pu Fen Xi. 2011 Aug;31(8):2036-9.
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.
高温退火和Cs/O激活是外部激励因素，而GaN材料的性质是制备负电子亲和势GaN光电阴极的内部因素。基于均匀掺杂和梯度掺杂负电子亲和势GaN光电阴极结构之间的差异以及GaN光电阴极激活过程中的光电流变化和成功激活后的量子产率，分析了两种结构光电阴极性能的异同。实验表明：梯度掺杂GaN光电阴极在激活过程中的光电流增长率较慢、激活时间较长，成功激活后的量子效率分别高于均匀掺杂光电阴极。场辅助光电阴极发射模型可以解释两者之间的差异，梯度掺杂结构的内建电场产生额外的电子向光电阴极表面漂移，相应地提高了电子到达光电阴极表面的概率。
