Theory for the Photoemission from a Space-Charge Region of a Semiconductor

Abstract

A theory is developed for evaluation of the effect of a space-charge region on photoemission from semiconductors. Such effect is shown to be significant in many cases and leads to the conclusions: (1) a "tail" should extend beyond the normal threshold region; (2) the energy of the valence band edge cannot, in general, be inferred from the observed threshold; (3) positive and negative space-charge regions cause effects which may not be symmetrical; (4) power-law fits to photoemission data near the threshold are of doubtful validity. It is shown that several anomalous results appearing in the literature can be explained by the space-charge effect.