QUANTUM YIELD OF GaAs SEMITRANSPARENT PHOTOCATHODE

The quantum yield of a semiconductor thin-film photocathode, operating in the transmission mode, has been derived from the continuity equation and light multiple reflections within the film and the substrate. The fit between experiment and theory is good for hv<1.7 eV. The differences between experiment and theory are explained in terms of the nonuniform population of defect states within the film. Electron diffusion lengths are found to be 0.3μ for the 1×1019 Zn-doped 2.5-μ -thick film and 0.1μ for the 3×1019 Zn-doped 0.85-μ -thick film, respectively.