Evolution of D0 and non-D0 light induced defect states in a-Si:H materials and their respective contribution to carrier recombination
Materials Research Society Symposium Proceedings
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A study has been carried out on the evolution of light induced defects in protocrystalline (diluted) a-Si:H films under 1 sun illumination. A room temperature reversal is observed in the photocurrents at 25°C, which is consistent with the relaxation in the recombination currents on corresponding p-i-n solar cells. It is also consistent with the pressure of "fast" states such as have been observed after high intensity illumination. Even with the limitations imposed by the relaxation in the light induced changes on the subgap absorption measurements, the evolution of distinctly different gap states centered around 0.9 and 1.15eV from the conduction band was identified. The kinetics of the electron occupied states, kN(E), at these two energies is compared with that of the neutral dangling bond (D0) densities as measured with electron spin resonance. Because of the similarity between the preliminary results of these kinetics it has not been possible to identify which states correspond to the D0 nor to draw any reliable conclusions about the nature of the different states.