In order to develop the photodetector for effective blue-green response, the 18-mm-diameter vacuum image tube combined with the transmission-mode Alo.7Gao.3Aso.9Po.1/GaAso.9Po.1 photocathode grown by molecular beam ep...In order to develop the photodetector for effective blue-green response, the 18-mm-diameter vacuum image tube combined with the transmission-mode Alo.7Gao.3Aso.9Po.1/GaAso.9Po.1 photocathode grown by molecular beam epitaxy is tentatively fabricated. A comparison of photoelectric property, spectral characteristic and performance parameter be- tween the transmission-mode GaAsP-based and blue-extended GaAs-based photocathodes shows that the GaAsP-based photocathode possesses better absorption and higher quantum efficiency in the blue-green waveband, combined with a larger surface electron escape probability. Especially, the quantum efficiency at 532 nm for the GaAsP-based photocathode achieves as high as 59%, nearly twice that for the blue-extended GaAs-based one, which would be more conducive to the underwater range-gated imaging based on laser illumination. Moreover, the simulation results show that the favorable blue-green response can be achieved by optimizing the emission-layer thickness in a range of 0.4 μm-0.6 μm.展开更多
提出了基于第一性原理的密度泛函理论框架下的广义梯度近似投影缀加波赝势法,在结构优化的基础上采用平板模型计算了GaAs(110)表面单一吸附0.5 ML Cs元素、单一吸附0.5 ML O元素及0.5 ML Cs、0.5 ML O共吸附系统的特定吸附位、吸附系统...提出了基于第一性原理的密度泛函理论框架下的广义梯度近似投影缀加波赝势法,在结构优化的基础上采用平板模型计算了GaAs(110)表面单一吸附0.5 ML Cs元素、单一吸附0.5 ML O元素及0.5 ML Cs、0.5 ML O共吸附系统的特定吸附位、吸附系统总能及吸附系统的电子结构。吸附系统总能的计算结果对比及电子结构图表明:当Cs、O元素吸附量在GaAs(110)表面达到Θ=1 ML时,它们并非各自在表面形成局域畴形态的竞争性共化学吸附,而是将在表面形成混合均匀相的协同共化学吸附。采用偶极子校正进一步计算三种吸附系统的功函数分别是4.423 e V、5.749 e V、4.377 e V,从而得出GaAs光电阴极制备过程中提高并保持光电阴极发射性能的方法及机理。展开更多
基金supported by the National Natural Science Foundation of China(Grant No.61301023)the Science and Technology on Low-Light-Level Nigh Vision Laboratory Foundation,China(Grant No.BJ2014001)
文摘In order to develop the photodetector for effective blue-green response, the 18-mm-diameter vacuum image tube combined with the transmission-mode Alo.7Gao.3Aso.9Po.1/GaAso.9Po.1 photocathode grown by molecular beam epitaxy is tentatively fabricated. A comparison of photoelectric property, spectral characteristic and performance parameter be- tween the transmission-mode GaAsP-based and blue-extended GaAs-based photocathodes shows that the GaAsP-based photocathode possesses better absorption and higher quantum efficiency in the blue-green waveband, combined with a larger surface electron escape probability. Especially, the quantum efficiency at 532 nm for the GaAsP-based photocathode achieves as high as 59%, nearly twice that for the blue-extended GaAs-based one, which would be more conducive to the underwater range-gated imaging based on laser illumination. Moreover, the simulation results show that the favorable blue-green response can be achieved by optimizing the emission-layer thickness in a range of 0.4 μm-0.6 μm.
文摘提出了基于第一性原理的密度泛函理论框架下的广义梯度近似投影缀加波赝势法,在结构优化的基础上采用平板模型计算了GaAs(110)表面单一吸附0.5 ML Cs元素、单一吸附0.5 ML O元素及0.5 ML Cs、0.5 ML O共吸附系统的特定吸附位、吸附系统总能及吸附系统的电子结构。吸附系统总能的计算结果对比及电子结构图表明:当Cs、O元素吸附量在GaAs(110)表面达到Θ=1 ML时,它们并非各自在表面形成局域畴形态的竞争性共化学吸附,而是将在表面形成混合均匀相的协同共化学吸附。采用偶极子校正进一步计算三种吸附系统的功函数分别是4.423 e V、5.749 e V、4.377 e V,从而得出GaAs光电阴极制备过程中提高并保持光电阴极发射性能的方法及机理。
