NEW FEATURES IN SPACE-CHARGE-LIMITED-PHOTOCURRENT TRANSIENTS

We present a theory of space-charge limited photocurrent transients generated by an instantaneous light pulse, in which the realistic absorption profile of the photogenerated charge is taken into account. This theory allows us to explain the following features, all observed experimentally but not predicted by the standard space-charge-limited-current theory: (a) the appearance of an initial current spike related to the screening of the electric field in the generation region; (b) a stronger light intensity dependence of the transit time and current caused by a decrease in the effective sample thickness; (c) the appearance of another kink in the space-charge-limited photocurrent transient related to the full charge reservoir extraction, which may be useful for investigation of the recombination losses in the generation region of, for example, hydrogenated amorphous silicon solar cells.