Light-induced creation of metastable defects in hydrogenated amorphous silicon studied by computer simulations of constant photocurrent measurements

The light-induced degradation of an intrinsic hydrogenated amorphous silico n sample has been studied from the evolution of the sub-band-gap absorption coefficient. The experimental results have been modeled using detailed num erical analysis, obtaining the defect distribution within the gap for each illumination time. These results have been compared with those previously o btained from a direct deconvolution of the absorption coefficient spectra [ J. A. Schmidt, R. Arce, R. H. Buitrago, and R. R. Koropecki, Phys. Rev. B 5 5, 9621 (1997)]. We have found, in agreement with our previous work, that ( i) the defect density shows the presence of more charged than neutral defec ts, as predicted by the defect pool model, and (ii) the concentration of ch arged and neutral defects evolve with the same time dependence, thus contra dicting Schumm's generalized model of defect equilibration. [S0163-1829(99) 08907-9].