Volume and Surface Recombination Rates for Injected Carriers in Germanium

Abstract

A study of bulk minority carrier lifetimes and surface recombination rates has been made, using experimental equipment similar to that of Navon, Bray, and Fan, wherein the time‐decay of carriers injected electrically by a pulse is observed. The diffusion theory for carriers of bulk lifetime τ has been worked out, considering a definite probability of nonrecombination, or reflection coefficient, to be associated with the surfaces of the sample. A simple relationship between this quantity and the surface recombination velocity has been derived. If the surface recombination velocity is known, the effective trapping area at the surface may be calculated from this relation. Values of bulk lifetime and surface recombination velocity have been found for both n‐ and p‐type germanium samples, and for a wide variety of surface treatments. By suitable modifications in experimental technique, this experiment may be utilized to measure drift mobility of minority carriers.