Photoelectric fatigue in electronic gallium arsenide

Experimental results are presented on the existence of photoelectric fatigue (PEF) in single-crystal n-GaAs with impurity band conduction at temperatures of 4.2-60 K. The PEF effect is explained by a model involving the inhomogeneous spatial distribution of recombination centers and slow-attachment centers, both on the semiconductor surface and in the space-charge region (SCR). This slow attachment is determined by the presence of surrounding potential barriers. The part of the latter for SCR centers is played by potential-relief maxima, arising in the 'rupture' of the metallic-type impurity band and the formation of 'metallic' drops, whose packing decreases with distance from the quasi-neutral volume. For attachment centers on the surface, the part of the potential barrier is played by the residual band-curvature on the semiconductor surface.