Influence of scattering on internal photoemission in heterostructures

Motivated by the capability of photoinjection as a working principle for infrared detectors and solar cells we study the effect of scattering processes on the charge transfer from the metal (Au) into the semiconductor. We argue that the injection probability is strongly enhanced by elastic isotropic scattering events. The presented predictions demonstrate that the magnitude of the internal quantum yield strongly depends on the Au layer thickness with the former being up to 20 times larger than in the case neglecting the isotropic elastic scattering events in the photoemitting layer. Concerning the Au/n-Si structure our model calculations show that the external quantum yield passes through a maximum at Au layer thicknesses of 40–60 Å, depending both on the ratio of lelp and the exciting photon energy. Subsequently, the external quantum yield was determined experimentally as a function of photon energy and the applied reverse bias voltage as well for Au/n-Si Schottky-diodes of different Au layer thicknesses ranging from 30 to 500 Å. There is a fairly good agreement between the presented calculations and the experimental results.