Experimental discrimination of geminate and non-geminate recombination in a-Si: H

A study of charge-carrier recombination in intrinsic hydrogenated amorphous silicon (a-Si:H) is presented using pulsed electrically and pulsed optically detected magnetic-resonance spectroscopies in order to measure the influence of spin-dependent recombination on photoluminescence (PL) and photoconductivity (PC). The experiments show band tail state recombination influencing the PL but not the PC which constitutes geminate recombination of correlated charge carriers that do not contribute to charge transport. In contrast, nongeminate recombination through silicon dangling bonds is observed influencing both PL and PC. The experiments presented constitute a direct and unambiguous observation of geminate and nongeminate recombination in a-Si:H.