METASTABLE EFFECTS IN THE DC CONDUCTIVITY OF HYDROGENATED AMORPHOUS-GERMANIUM

We report on the effect of thermal equilibration on the dark conductivity of undoped optimized a-Ge: H with an optical gap of 1.03 eV. The freeze-in temperature T(E) is about 160-degrees-C. The isothermal relaxation of the conductivity follows a stretched exponential function. The inverse equilibration time tau-1 is thermally activated with an energy E-tau of 1.4-1.5 eV. It is then shown that, as compared with the values for a-Si: H, T(E), tau and E-tau are only slightly different. The results are fully consistent with the model of dispersive diffusion of hydrogen.