DEFECT METASTABILITY IN HYDROGEN PASSIVATED POLYCRYSTALLINE SILICON

A comprehensive review is presented for the defect passivation and the light-induced metastability in fine grain polycrystalline silicon (poly-Si). The passivation kinetics of grain boundary defects were examined by electron spin resonance and secondary ion mass spectrometry measurements. The spin density decreases to a residual value which strongly depends on the passivation temperature and a further low-temperature anneal reduces the spin density to N S =2.2×10 16 cm −3 . Illumination with white light produces additional dangling bond defects which are metastable and can be removed by an anneal at moderate temperatures. The light-induced degradation decreases with repeated illumination and annealing cycles and is restored upon re-exposure to monatomic H. Our results provide the strongest evidence to date that hydrogen is responsible for the metastability in both poly-Si:H and hydrogenated amorphous silicon.

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