Electron beam-induced current measurements, at temperatures ranging from 50 to 300K, were used to study the effects of hydrogenation, P diffusion and annealing (various cooling rates) upon the recombination activity of dislocations. It was found that both hydrogenation and P diffusion caused a marked reduction in the room-temperature activity; with little change in the dislocation activity at lower temperatures. On the basis of the observed temperature dependences, it was concluded that the dislocation activity, initially dominated by deep centres, was controlled by shallow states (less than 0.1eV from the band edges) after these treatments. This effect was attributed to the passivation of deep levels, in the case of hydrogenation, and to the gettering of impurities in the case of P diffusion. It was also found that there was a marked effect, of the cooling rate, upon the behaviour of dislocations in multicrystalline material. Quenching led to significant room-temperature activity, thus indicating considerable contamination, whereas slow cooling resulted in a recombination behaviour that was characteristic of shallow states.

W.Seifert, K.Knobloch, M.Kittler: Solid State Phenomena, 1997, 57-58, 287-92