Light-induced modification of a-SiO_x:H. I: Metastability

The structural, electronic, optical, and electrical properties of amorphous silicon suboxides with oxygen concentrations between 0 and 44 were investigated with respect to light-induced metastability. Light-soaking experiments were performed by illuminating the a-SiO_x:H samples by above-band gap light for prolonged times at high intensities. It was found that metastable degradation proceeds more slowly in a-SiO_x:H, due to a higher concentration of stable defects caused by oxygen backbonding. A redshift of the absorption edge, which was irreversible for annealing below T≤300°C, was observed for multiple degradation cycles.