Non-radiative recombination in a-Si:H is studied by frequency-resolved photoluminescence spectroscopy (FRS) at excitation densities which are known to lead to geminate recombination. The measurements were performed between 4K-100K and the defect density was varied in the range 10(16)cm(-3)-5.10(17)cm(-3). The dependence of the lifetime distribution on the defect density at low temperature is quantitatively explained in a model where radiative recombination competes with non-radiative tunneling into defect states.
