Nonradiative recombination and its influence on the lifetime distribution in amorphous silicon (a-Si:H)

We present a detailed analysis concerning the influence of the defect density ${\mathit{N}}_{\mathit{D}}$ on the low-temperature (T=10 K) geminate recombination kinetics. It is shown that the lifetime distribution of a-Si:H, measured by frequency-resolved photoluminescence spectroscopy, can be explained quantitatively if it is assumed that radiative recombination is directly competing with nonradiative tunneling into defect states. This allows us to determine the radiative lifetime distribution with high accuracy, which in turn provides the unique opportunity to describe the recombination kinetics entirely, i.e., including its nonradiative contribution. Interesting and nonintuitive consequences that are related to the competition model are discussed.