Light-induced defect creation in hydrogenated polymorphous silicon during repeated cycles of illumination and annealing

We have examined how the intensity of the ESR signal associated with dangling bonds in hydrogenated polymorphous silicon is affected by repeating light-soaking (LS) and 100°C annealing cycles. It was found that the light-induced degradation efficiency decreases with repeated LS-100°C annealing cycles. This result is accounted for in terms of the termination of dangling bonds by mobile hydrogen, i.e. the termination is enhanced by more mobile hydrogen as a result of modification of the amorphous network by the LS-annealing cycles, and consequently the net light-induced defect creation rate is reduced. This is in contrast with previous models in which the decrease in the light-induced degradation efficiency on repeated LS-annealing cycles is attributed to an increase in the amount of hydrogen being ineffective for light-induced defect creation.