The conventional field approach, used to describe the dynamic equilibrium of gases and solid-state masers, is applied to photoconducting solids. The dynamics of such systems can be treated with none of the inherent limitations of the traditional phenomenological approach. The significance of capture cross sections and attempt-to-escape frequencies can be appreciated, stimulated recombination evaluated, and phenomenological quantities can be given physical significance. A correlation between optical cross sections and capture coefficients is simply derived, which is absent in earlier models.

• Received 6 February 1967

DOI:https://doi.org/10.1103/PhysRev.159.540