Keywords: 
• GaN光电阴极 /
• 量子效率衰减 /
• 发射电子能量分布 /
• 表面势垒

Abstract: Quantum efficiency decay of reflection-mode GaN photocathode is small at short wavelengths and large at long wavelengths. In light of this experimental phenomenon, the emitted electron energy distribution is calculated by using the Boltzmann distribution and transfer matrix method based on Airy function, with the intervalley scattering considered. The effect of surface potential barrier change on quantum efficiency decay is investigated. The results of theoretical calculation are in good agreement with the experimental results. The reduction of effective dipole in activated layer leads to increased length and height of surface barrier, which causes more decay of the emitted electron energy distribution generated by longer wavelength photons, and less decay of the emitted electron energy distribution generated by shorter wavelength photons. It is the fundamental reason of phenomenon that the decay of quantum efficiency is small at short wavelengths and large at long wavelengths.