Identification of non-radiative recombination paths in microcrystalline silicon (μc-Si:H)

We report on a study of photoconductivity, electron spin resonance (ESR) as well as electrically detected magnetic resonance (EDMR) on nominally undoped μc-Si:H deposited by the hot-wire technique. At low temperature (T < 50 K) there are similarities in the properties of μc-Si:H and a-Si:H. We conclude that the g = 1.998 center, formerly assigned to conduction electrons, CE, monitored by ESR is a shallow localized state close to the conduction band and that recombination follows distant pair kinetics. According to EDMR the relevant recombination step is tunneling from CE states to neutral Si dangling bonds. At T < 50 K photoconductivity arises from hopping transport in localized band tail states.