Effect of Absorptivity on Quantum Efficiency of Transmission-Mode GaAs Photocathode

According to the analysis of transmission-mode GaAs photocathode optics and photoelectric emission properties, the photoelectrons that participate in photoelectric emission are derived from the absorptive photon combining the theory of "photoelectric emission three-step model". The relationship between the absorptivity and spectral response curve is studied on the transmission-mode GaAs photocathode. The factor in the original quantum efficiency formula (1 - R
hν
) should theoretically be modified as A
hν
. There, R
hν
and A
hν
are respectively the reflectivity and absorptivity of photocathode, which are functions of photon wavelength, film thickness and optical constant. According to the experimental reflectivity and transmittance, the experimental value of absorptivity was calculated, substituted into the quantum efficiency formula for fitting calculation. The difference between theoretical and experimental quantum efficiency was analyzed. And the influence of film interference on photocathode absorptivity and quantum efficiency was proposed. The relationship between the quantum efficiency and the absorptivity was analyzed in the paper.