INFLUENCE OF SCATTERING ON INTERNAL PHOTOEMISSION IN HETEROSTRUCTURES

Motivated by the capability of photoinjection as a working principle f or infrared detectors and solar cells we study the effect of scatterin g processes on the charge transfer from the metal (Au) into the semico nductor. We argue that the injection probability is strongly enhanced by elastic isotropic scattering events. The presented predictions demo nstrate that the magnitude of the internal quantum yield strongly depe nds on the Au layer thickness with the former being up to 20 times lar ger than in the case neglecting the isotropic elastic scattering event s in the photoemitting layer. Concerning the Au/n-Si structure our mod el calculations show that the external quantum yield passes through a maximum at Au layer thicknesses of 40-60 Angstrom, depending both on t he ratio of l(e)/l(p) and the exciting photon energy. Subsequently, th e external quantum yield was determined experimentally as a function o f photon energy and the applied reverse bias voltage as well for Au/n- Si Schottky-diodes of different Au layer thicknesses ranging from 30 t o 500 Angstrom. There is a fairly good agreement between the presented calculations and the experimental results.