SUB-POISSON PHOTOELECTRON STATISTICS IN SATURATED LIGHT-ABSORPTION

We show that sub-Poisson photoelectrons can result from the finite rel axation time of the fundamental photoelectron-emitting entities, which could be individual atoms, or valence-band electrons, etc., depending on the type of the detectors. After identifying the precise quantum-m echanical criterion for a light without the intrinsic antibunching pro perty, it is demonstrated that the variance to mean ratio of photoelec tron counts within a fixed time period can be reduced to as small as 1 /2, even for such light. The condition for strong fluctuation reductio n is found to be the saturation of light absorption. Semiconductor pho todetectors are considered in relative details, and their photoelectro n statistics are expressed in terms of the intrinsic material paramete rs.