CHARACTERIZATION OF THE ELECTRON INTERACTION WITH ZNSE SURFACE-STATES BY THE PHOTO-VOLTAIC MODULATION OF LOW-ENERGY-ELECTRON TRANSMISSION

When low-energy electrons are incident on a solid surface, some are reflected and some are transmitted. In the case of semiconductors, the number that are transmitted can be photovoltaically modulated with incident light. The time dependence of this modulated transmitted current has been examined for undoped, singlecrystal ZnSe, and is found to consist of two components, the relative size of which depends on the light intensity, electron flux, and electron energy. A theoretical model that satisfactorily accounts for the observed phenomena involves an accumulation space-charge region at the ZnSe surface and a surface state whose electronic population can change due to its interaction with low-energy electrons that are incident on the surface. © 1979 The American Physical Society.