REVERSIBLE PHOTOINDUCED STRUCTURAL-CHANGE IN HYDROGENATED AMORPHOUS-SILICON

A reversible photo-induced change has been observed in the polarizatio n dependence of a transverse electro-absorption signal for hydrogenate d amorphous silicon, which is indicative of the occurrence of structur al change in the whole material. The change proceeds rapidly under ste ady light exposure until saturation is reached, while the decrease in the photoconductivity becomes significant just after saturation. These observations convince us that a large-scale photostructural change is involved in the photo-induced degradation of the electronic propertie s of the material in addition to the creation of metastable dangling b ond defects.