The optimal thickness of a transmission-mode GaN photocathode
The optimal thickness of a transmission-mode GaN photocathode
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DOI：
10.1088/1674-1056/21/8/087901
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发表时间：
2012-08
影响因子：
1.7
通讯作者：
Xiaohui Wang;F. Shi;Hui Guo;Cang-lu Hu;Hongchang Cheng;Benkang Chang;L. Ren;Yujie Du;Junju Zh
中科院分区：
文献类型：
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作者：
Xiaohui Wang;F. Shi;Hui Guo;Cang-lu Hu;Hongchang Cheng;Benkang Chang;L. Ren;Yujie Du;Junju Zh
利用Cs/O对Mg掺杂浓度为1.6 × 1017 cm-3、厚度为150 nm的GaN光电阴极进行活化，得到了GaN光电阴极的负电子亲和势透射模式（t模式）的量子效率（QE）曲线。在290 nm处量子效率最大，达到13.0%。根据扩散方程解出的t型QE方程，拟合出了QE曲线。根据拟合结果，电子逃逸概率为0.32，背界面复合速度为5 × 104 cms-1，电子扩散长度为116 nm。在此基础上，模拟了GaN厚度对t模量子效率的影响。模拟结果表明，GaN的最佳厚度为90 nm，优于150 nm的GaN。
A 150-nm-thick GaN photocathode with a Mg doping concentration of 1.6 × 1017 cm−3 is activated by Cs/O in an ultrahigh vacuum chamber, and a quantum efficiency (QE) curve of the negative electron affinity transmission-mode (t-mode) of the GaN photocathode is obtained. The maximum QE reaches 13.0% at 290 nm. According to the t-mode QE equation solved from the diffusion equation, the QE curve is fitted. From the fitting results, the electron escape probability is 0.32, the back-interface recombination velocity is 5 × 104 cms−1, and the electron diffusion length is 116 nm. Based on these parameters, the influence of GaN thickness on t-mode QE is simulated. The simulation shows that the optimal thickness of GaN is 90 nm, which is better than the 150-nm GaN.