Electron Affinity of Single-Crystalline Chemical-Vapor-Deposited Diamond Studied by Ultraviolet Synchrotron Radiation

Abstract

We have investigated the electron affinity of (111) and (100) single crystalline surfaces of chemical-vapor-deposited diamond with additional treatments. For specimens exposed to hydrogen plasma (H treatment), the electron affinities are found to be negative from photoyield spectra using ultraviolet synchrotron radiation light, because the threshold energies of photoyield from these specimens are located at an energy of h ?< 5.5 eV, which is the indirect band-gap energy of diamond. The threshold energies of photoyield from surfaces annealed in oxygen atmosphere at 500?C are higher than those from H-treated surfaces. This can be explained in terms of an increase of work function of the oxygen-adsorbed surfaces.