Comparative Study of Uniform-Doping and Gradient-Doping Negative Electron Affinity GaN Photocathodes
LI Biao1, CHANG Ben-kang1*, XU Yuan1, DU Xiao-qing2, DU Yu-jie1, FU Xiao-qian1, WANG Xiao-hui1, ZHANG Jun-ju1
1. Institute of Electronic Engineering and Optoelectronic Technology, Nanjing University of Science and Technology, Nanjing 210094, China 2. College of Optoelectronic Engineering, Chongqing University, Chongqing 400030, China
Abstract：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.
Key words：Negative electron affinity;GaN;Uniform-doping;Gradient-doping;Photocathode;Field-assisted;Quantum efficiency
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 . 均匀掺杂和梯度掺杂结构GaN光电阴极性能对比研究[J]. 光谱学与光谱分析, 2011, 31(08): 2036-2039.
LI Biao1, CHANG Ben-kang1*, XU Yuan1, DU Xiao-qing2, DU Yu-jie1, FU Xiao-qian1, WANG Xiao-hui1, ZHANG Jun-ju1 . Comparative Study of Uniform-Doping and Gradient-Doping Negative Electron Affinity GaN Photocathodes . SPECTROSCOPY AND SPECTRAL ANALYSIS, 2011, 31(08): 2036-2039.
[1] DU Xiao-qing, CHANG Ben-kang, ZOU Ji-jun(杜晓晴, 常本康, 邹继军). Acta Optica Sinica(光学学报), 2005, 25(10): 1411. [2] Bakin V V, Pakhnevich A A, Zhuravlev A G. Journal of Surface Science and Nanotechnology, 2007, 5: 80. [3] Iwaya M, Takeuchi T, Yamaguchi S. Jpn. J. Appl. Phys., 1998, 37: L316. [4] Nakcmura S, Mukai T, Senoh M. Jpn. J. Appl. Phys., 1992, 31: L139. [5] ZOU Ji-jun, CHANG Ben-kang. Optical Engineering, 2006, 45(5): 054001-1. [6] Machuca F, Liu Zhi, Sun Yun. Journal of Vac. Sci. Technol. A, 2002, 20(5): 1784. [7] Tereshchenko O E, Shaǐbler G E, Yaroshevich A S. Physics of the Solid State, 2004, 46(10): 1949. [8] King S W, Barnak J P, Bremser M D. J. Appl. Phys., 1998, 84(9): 5248. [9] QIAO Jian-liang, TIAN Si, CHANG Ben-kang(乔建良, 田 思, 常本康). Acta Physica Sinica(物理学报), 2009, 58(8): 5847. [10] Zhi Yang, Benkang Chang, Jijun Zou. Applied Optics, 2007, 46(28): 7035. [11] Yijun Zhang, Benkang Chang, Zhi Yang. Applied Optics, 2009, 48(9): 1715. [12] Mnatsakanov T T, Levinshtein M E, Pomortseva L I. Solid-State Electronics, 2003, 47(2): 111. [13] Burt M G, Inkson J G. Journal of Physics D: Applied Physics, 1976, 9: 43. [14] GU Zu-yi, TIAN Li-lin, FU Li-wen(顾祖毅，田立林，富力文). Semiconductor Physics(半导体物理学). Beijing: Publishing House of Electronics Industry(北京：电子工业出版社), 1995. 130.
