Space-charge-limited photocurrent transients: The influence of bimolecular recombination

Abstract

Recently we presented a detailed theory of the space-charge-limited current (SCLC) transients generated by an instantaneous pulse of light, in which the realistic absorption profile has been taken into account. In this paper we present a theory that, in addition, takes into account the bimolecular recombination and the value of the detection resistor. This allowed us to propose a convenient method to study the fast recombination by electrical instead of the usual optical techniques. The method allowed us to present experimental results related to subnanosecond nonradiative bimolecular recombination in amorphous hydrogenated silicon (a-Si:H) and to discuss the microscopic origin of bimolecular recombination. The importance of understanding bimolecular recombination in a-Si:H is underscored by the fact that bimolecular recombination is the driving force of a-Si:H degradation.