GENERATION, RECOMBINATION, AND IONIZATION IN SILICON AND GERMANIUM-CRYSTALS - KINETICS OF NONEQUILIBRIUM CARRIERS

The kinetics of the laser excitation of nonequilibrium carriers is studied. The recombination of nonequilibrium carriers, linear recombination, and the formation and ionization of excitons are taken into account. Approximate asymptotic expressions are derived for the concentration of nonequilibrium carriers through an expansion of the solutions of singularly perturbed systems in a small parameter. These expressions are valid over the entire ranges of the length and intensity of the laser pulse. This is the first derivation of such expressions. The nature of the singular point of the system has been identified through a qualitative analysis of dynamic systems. The ranges of the laser pulse intensity and of the kinetic coefficients, in which a given type of solution (oscillatory or nonoscillatory) is possible, have been determined. These asymptotic estimates can be used, in a comparison with experimental results, to find indirect, crude estimates of probabilities (cross sections) for recombination and ionization processes.