Charge limitation effects in emission from semiconductor photocathodes at inhomogeneous excitation

摘要

Photoemission from a semiconductor with negative electron affinity surface is investigated theoretically for the case of local excitation regime and Gaussian distribution of the light intensity over a sample surface. While the maximum emission current is an exponential function of the negative electron affinity value, the inhomogeneous intensity distribution results in smoothed dependence of the emission current on the light intensity in the region of maximum current. The relaxation processes to the stationary emission and the cathode restoring time are found to be less sensitive to light non-homogeneity due to photovoltage level over the surface.