Comparative research on reflection-mode GaAs photocathode with graded Al_xGa_{1鈭?span style='font-style: italic'>x}As buffer layer

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• 作者：Liang Chen^a ; ^b ; ^{52571497@qq.com" class="auth_mail" title="E-mail the corresponding author} ; Yang Shen^a ; Shuqin Zhang^a ; Yunsheng Qian^b ; Sunan Xu^a
• 关键词：160.2100 ; 250.0250
• 刊名：Optics Communications
• 出版年：2015
• 出版时间：15 November 2015
• 年：2015
• 卷：355
• 期：Complete
• 页码：186-190
• 全文大小：750 K

文摘

The graded Al compositional Al_xGa_1−xAs buffer layer can not only form continuous internal electric field from buffer layer to active layer but also optimize the interface properties by decreasing the misfit dislocations and stacking faults arising from lattice mismatch. By measuring the spectral response current (SRC) for two reflection-mode (r-mode) designed samples of graded and stationary Al compositional structure, we can find the special phenomenon that the graded structure had quite influence at the middle wavelength band from 550 nm to 850 nm, but not the short wavelength band from 400 nm to 550 nm, though the buffer layer can only absorb photon energy at the short wavelength band. Through the comparative research for designed samples through SPV before Cs–O activation and SRC after Cs–O activation, the graded structure can well optimize the key parameters such as L_D, L_n, S_v and P. For the photon absorption lengths are relative little at the short wavelength band and relative long at the middle wavelength band, so the optimizations of key parameters have little influence on photo-excited electrons at the short wavelength band which are mainly excited from the region in active layer near surface barriers. The optimizations of key parameter, mainly the back interface recombination velocity (S_v), can have quite impact on photo-excited electrons at the middle short wavelength band which are mainly excited from the internal active layer near the back interface. This comparative research can help to well study the photo-emission theory and structure design on graded Al compositional design for r-mode GaAs photocathodes in the future research.