It was recalled that the light-induced degradation of amorphous Si solar cells could be reversed by applying a strong electric field in the dark, and that the rate of reversal increased with field-strength, temperature, and light intensity. The activation energy for annealing the dark degradation was reduced from about 1.34eV, under open-circuit conditions, to 1.16eV when a strong reverse bias was applied. When degraded cells were exposed to intense illumination, in addition to a strong reverse bias, the activation energy for the recovery of performance decreased to about 0.77eV. Both light-induced degradation and degradation reversal could be explained in terms of a model that was based upon proton motion within a metastable defect complex.

D.E.Carlson, K.Rajan: Journal of Applied Physics, 1998, 83[3], 1726-9