Simple Model for Internal Photoemission

We have studied the influence of film thickness and collision processes upon the internal photoemission process in metal-semiconductor systems. A simple, one-dimensional random walk model has been used. The analysis shows that significantly larger yields may be expected for film thicknesses of the order of or less than electron-phonon mean free paths. The influence of energy dependent mean free paths has also been studied. The results are in qualitative agreement with the results of Fermi-age theory, but are somewhat different quantitatively.