Kinetics of distant-pair recombination: Application to amorphous silicon

Abstract

We present an exact solution for the decay of randomly distributed excited carriers, and find that a monomolecular, distant-pair approximation is valid over a wide range of excitation powers. Under repetitively pulsed or continuous excitation, an accumulated pair population is present, the result of which is that the decay curve varies at high excitation power but is independent of excitation power at low power. In consequence, time-resolved experiments cannot distinguish between distant-pair and geminate recombination, and frequency-resolved methods must be used. We find that distant-pair recombination provides a quantitative explanation of the experimental results in a-Si:H.