Photocurrent and carrier distributions due to steady light absorbed in finite thickness

The steady-state photocurrent through a layer of photoconducting material is investigated when one of the surfaces is illuminated by a constant light source. The material is assumed to be intrinsic and free of deep traps, light penetration is characterized by an optical absorption coefficient, and bulk recombination is taken into account. In the presence of an applied electric field, it is seen that the experimentally accessible photoinjection efficiency can be interpreted as the product of a free-carrier generation efficiency and a recombination yield. Cases which approximate monomolecular recombination and bimolecular recombination are treated in detail. The results show the free-carrier distributions and the dependence of the recombination yield on absorption coefficient, field, both carrier mobilities, and the recombination constant. This dependence is seen to be rather similar to the case of very fast pulsed light for monomolecular recombination but quite different for bimolecular recombination. © 1972 The American Institute of Physics.