Coexistence of geminate and non-geminate recombination in a-Si:H and a-Ge:H observed by quadrature frequency resolved spectroscopy

In addition to well known double-peak lifetimes (∼ms and ∼μs) of photoluminescence (PL) observed at low temperatures in a-Si:H and a-Ge:H, a third peak at ∼0.1–160 s has been discovered with quadrature frequency resolved spectroscopy (QFRS), even under the geminate recombination condition. Steady-state carrier density deduced from the third component of PL gives the sublinear dependence of carrier generation rate G, which is correlated with the intensity of light-induced electron spin resonance (LESR). Coexistence of geminate (involving exciton-like) and non-geminate recombinations is suggested in the present materials.