Hydrogen Passivation Effect on Enhanced Luminescence from Nanocrystalline Si/SiO₂ Multilayers

Nanocrystalline Si/SiO₂ multilayers are prepared by thermally annealing amorphous Si/SiO₂ stacked structures. The photoluminescence intensity is obviously enhanced after hydrogen passivation at various temperatures. It is suggested that the hydrogen trapping and detrapping processes at different temperatures strongly influence the passivation effect. Direct experimental evidence is given by electron spin resonance spectra that hydrogen effectively reduces the nonradiative defect states existing in the Si nanocrystas/SiO₂ system which enhances the radiative recombination probability. The luminescence characteristic shows its stability after hydrogen passivation even after aging eight months.