DEFECT EQUILIBRATION AND METASTABILITY IN LOW-SPIN-DENSITY AMORPHOUS HYDROGENATED SILICON

Electron spin resonance was used to characterize concentrations of thermal equilibrium defects from room temperature to 280-degrees-C in a 60-mu-m thick hydrogenated amorphous silicon film. A defect formation energy of 0.35 eV was found in material with 1 X 10(15) cm-3 spins at 190-degrees-C. Annealing of defects quenched in from 250-degrees-C revealed an activation energy of 2.2 eV. Annealings at 150-degrees-C of defects quenched in at 250-degrees-C and 190-degrees-C were compared; the additional defects introduced at the higher temperature annealed 10 times faster, supporting a model in which metastable states with higher formation energies have smaller annealing activation energies. Light-induced defects are described in terms of a very "high-temperature" distribution similar to that which might be quenched in as a result of kT almost-equal-to 0.5 eV.