Metastable defect kinetics in microcrystalline silicon

Cooling rate dependent changes of the dark conductivity. sigma(D), were measured in muc-Si. Upon thermal quenching from 440 to 100 K sigma(D) increases by two orders of magnitude. This frozen-in state is reversible. Annealing at 440 K followed by a slow cool completely restores the initial state. Since H-depleted samples do not exhibit any influence on sigma(D) due to thermal treatment prior to the measurement the effect has to be related to the presence of hydrogen. The time and temperature dependence of the relaxation of the quenched-in state reveals two competing processes. At short times sigma(D) increases due to the activation of a donor complex and at long times sigma(D) decreases due to the dissociation of bond-center H complexes. (C) 2002 Elsevier Science B.V. All rights reserved.