Zou Jijun, Zhang Yijun, Deng Wenjuan, Jin Jieyun, Chang Benkang
Engineering Research Center of Nuclear Technology Application (East China Institute of Technology), Ministry of Education, Nanchang, Jianxi, China.
Appl Opt. 2011 Sep 20;50(27):5228-34. doi: 10.1364/AO.50.005228.
The quantum efficiency equations of two different structure reflection-mode GaAs photocathodes with back interface recombination velocity have been solved from the diffusion equations. One structure consists of GaAs substrate and an epitaxial GaAs active layer (GaAs-GaAs) and another structure consists of GaAs substrate, an epitaxial AlGaAs buffer layer, and a GaAs active layer (AlGaAs-GaAs). The experimental results show that the quantum efficiency of long-wavelength photons and the integral sensitivities for GaAs-GaAs cathodes both increase with the increase in the active layer thickness, which is due to the increase of electron diffusion length. The quantum efficiency of long-wavelength photons and the integral sensitivity of AlGaAs-GaAs cathodes are greater than those of GaAs-GaAs cathodes with an identical active layer thickness, which is attributed to the AlGaAs buffer layer. The buffer layer can reflect electrons and improve the quality of the GaAs active layer. Through the theoretical simulation, we found the active layer thickness for AlGaAs-GaAs cathodes has an optimum value at which the cathodes achieve the maximum sensitivity.
从扩散方程求解了具有背界面复合速度的两种不同结构反射模式砷化镓光电阴极的量子效率方程。一种结构由砷化镓衬底和外延砷化镓有源层（GaAs-GaAs）组成，另一种结构由砷化镓衬底、外延铝镓砷缓冲层和砷化镓有源层（AlGaAs-GaAs）组成。实验结果表明，GaAs-GaAs阴极的长波长光子量子效率和积分灵敏度均随有源层厚度的增加而增加，这是由于电子扩散长度增加所致。有源层厚度相同时，AlGaAs-GaAs阴极的长波长光子量子效率和积分灵敏度大于GaAs-GaAs阴极，这归因于AlGaAs缓冲层。该缓冲层可以反射电子并提高砷化镓有源层的质量。通过理论模拟，我们发现AlGaAs-GaAs阴极的有源层厚度存在一个最佳值，在此值下阴极可实现最大灵敏度。
