Two characteristic photoluminescence states in a-Si:H and its alloys

Photoluminescence (PL) in a-Si:H and its alloys exhibits interesting characteristics related to the metastability of a disordered material. Two lifetime components, which are characterized with respective specific peak lifetimes of about 1 ms and 10 μs are commonly observed in a PL-lifetime distribution throughout the systems, irrespective of their difference in a localized tail-state distribution. With the aid of the modulated IR-absorption measurement that can detect structural instability in the vicinity of the Si-H bond, the characteristics of the two lifetime components are discussed based on the model that the PL corresponding to those lifetime components is caused by a localized PL center associated with some special structural unit.