Light-induced defect creation is demonstrated in hydrogenated polycrystalline silicon (poly-Si:H). The newly created defects are metastable as in hydrogenated amorphous silicon (a-Si:H). However, unlike a-Si:H the magnitude of the light-induced degradation decreases with repeated illumination and anneal cycles and is restored upon reexposure to monatomic hydrogen. This unique response arises from the inherent structural inhomogeneity of the polycrystalline material and establishes that hydrogen directly contributes to the metastability in poly-Si:H.

• Received 24 June 1993

DOI:https://doi.org/10.1103/PhysRevLett.71.2733