Temperature Dependence of the Photoconductive Lifetime in n-Type Gallium Arsenide

Abstract

Temperature dependences of electron lifetimes in n-type GaAs of 0.05 to 0.3 Ωcm were investigated using measurements of photoconductivity and Hall effect in the temperature range from 350° to 100°K. The electron lifetime increased with decreasing temperature and showed saturation at low temperatures with a plateau at intermediate temperatures. Theoretical derivations of the electron lifetime were also carried out for two cases; one is the case in which there exists an acceptor-type recombination level besides a recombination level near the midgap and the other is the case in which there exist two hole-trapping levels besides a recombination level near the midgap. Experimental results were successfully explained by these models and six species of acceptors were found, the depths of which were 0.33, 0.2, 0.13, 0.085, 0.06, and 0.02 eV. The saturation of the electron lifetime at low temperatures could be attributed to recombination through the acceptor level. The electron capture cross sections of the acceptors were estimated.