Distribution of carriers in gradient-doping transmission-mode GaAs photocathodes grown by molecular beam epitaxy
Distribution of carriers in gradient-doping transmission-mode GaAs photocathodes grown by molecular beam epitaxy
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DOI：
10.1088/1674-1056/18/10/074
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发表时间：
2009-10
影响因子：
1.7
通讯作者：
Zhang Yijun;Chang Benkang;Yang Zhi;Niu Jun;Zou Jijun
中科院分区：
文献类型：
--
作者：
Zhang Yijun;Chang Benkang;Yang Zhi;Niu Jun;Zou Jijun
首次采用梯度掺杂结构制备透射式GaAs光阴极，密封像管的积分灵敏度达到1420 μA/lm。采用电化学电容-电压剖面法研究了分子束外延（MBE）生长后的梯度掺杂透射式GaAs光电阴极内部载流子浓度分布。结果表明，采用分子束外延生长可以获得理想的梯度掺杂结构。计算了掺杂浓度为1 × 1019 cm-3 ~ 1 × 1018 cm-3的梯度掺杂GaAs有源层的总能带弯曲能为46.3 meV，这有助于改善薄外延层的光激发电子向表面的运动。此外，通过对能带偏移的分析，发现GaAs和GaAlAs之间载流子浓度的差异导致背界面电子势垒降低，从而减少了高能光电子的数量，影响了短波响应。
The gradient-doping structure is first applied to prepare the transmission-mode GaAs photocathode and the integral sensitivity of the sealed image tube achieves 1420 μA/lm. This paper studies the inner carrier concentration distribution of the gradient-doping transmission-mode GaAs photocathode after molecular beam epitaxy (MBE) growth using the electrochemical capacitance-voltage profiling. The results show that an ideal gradient-doping structure can be obtained by using MBE growth. The total band-bending energy in the gradient-doping GaAs active-layer with doping concentration ranging from 1 × 1019 cm−3 to 1 × 1018 cm−3 is calculated to be 46.3 meV, which helps to improve the photoexcited electrons movement toward surface for the thin epilayer. In addition, by analysis of the band offsets, it is found that the worse carrier concentration discrepancy between GaAs and GaAlAs causes a lower back interface electron potential barrier which decreases the amount of high-energy photoelectrons and affects the short-wave response.