The High Quantum Efficiency of Exponential-Doping AlGaAs/GaAs Photocathodes Grown by Metalorganic Chemical Vapor Deposition

An exponential-doping structure is successfully applied to the preparation of AlGaAs/GaAs photocathodes through the metalorganic chemical vapor deposition (MOCVD) technique. The experimental results show that the quantum efficiency in the entire waveband region for the exponential-doping photocathodes grown by MOCVD is remarkably enhanced as compared to those grown by molecular beam epitaxy. As a result of the improved built-in electric fields and cathode performance parameters, the photoemission characteristics for the MOCVD-grown transmission-mode and reflection-mode AlGaAs/GaAs photocathodes are different over the wavelength region of interest.