Study of the metastable light-induced changes in hydrogenated amorphous silicon by capacitance measurements

The density of defect states at the Fermi level, g(E_F), has been determined by capacitance vs. temperature (C-T) experiments carried out at different frequencies for a series of a-Si:H and a-SiGe:H samples. The films were deposited at different temperatures in a Schottky configuration, and they were investigated in both the annealed state and the light-soaked state. Coplanar conductivity measurements and infrared analysis were also carried out. Pronounced changes in g(E_F) as measured by the C-T technique have been attributed to the creation of metastable defects other than neutral DBs following light exposure. The hydrogen content plays an important role in determining the amount of the change.