科研之友
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摘要
Using the modulation transfer function obtained by establishing and solving the two-dimensional continuity equation, we have calculated and comparatively analysed the resolution characteristics of transmission-mode exponential-doping and uniform-doping GaAs photocathodes. The calculated results show that, compared with the uniform-doping GaAs photocathode, the exponential-doping structure can upgrade significantly not only the resolution but also the quantum efficiency of a negative electron affinity GaAs photocathode. This improvement differs from the method for high resolution by reducing the emission layer T-e and the electron diffusion length L-d, or by increasing the recombination velocity of back-interface S-v,, which leads to a low quantum efficiency. Moreover, the improvement of resolution and quantum efficiency for transmission-mode exponential-doping GaAs photocathode is the result of facilitating the electron transport and restraining the lateral diffusion by the built-in electric field.
