Saturation behavior of the light-induced defect density in hydrogenated amorphous silicon (solar cells)

The light-induced generation of defects in a-Si:H(F) was saturated by a few hours of illumination with Kr-ion-laser light soaking ( lambda =647.1 nm) near room temperature. The time to reach saturation scales roughly with 1/G/sup 2/, but the saturation value is essentially independent of the illumination intensity. Therefore, the saturation is not due to thermal annealing. The saturation values of the light-induced defect density in 37 a-Si:H(F) samples which had been grown in six different reactors over a range of conditions were measured. These a-Si:H(F) samples have annealed-state defect densities in the range of 1.1*10/sup 15/ to 1.6*10/sup 16/ cm/sup -3/, Urbach energies of 42-62 meV, and Tauc optical bandgaps of 1.61 to 1.83 eV. The saturation value rises from 5*10/sup 16/ to 2*10/sup 17/ cm/sup -3/ with increasing optical gap and total hydrogen content, but it is not correlated with the Urbach energy or with the annealed-state defect density.<
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