Oxidation of nanocrystalline silicon at room temperature and various humidity

Oxidation of HF vapor-etched nanocrystalline silicon films, prepared by drop coating from nanocrystalline Si sol in acetonitrile, was studied. Oxidation of nc-Si at room temperature in air with 5% and 86% relative humidity was observed by means of IR spectroscopy for 2 days. The change in film mass after 15 hours of oxidation was determined using quartz crystal microbalance. In dry air, film mass and integral intensity of bands attributed to vibrations in Si3-x‒Si‒Hx and Si-O-Si groups changed linearly with time. In humid air, intensity of in Si3-x‒Si‒Hx band decays exponentially and intensity of Si-O-Si band increases as a square root of oxidation time. Film mass gain after 15 hours of oxidation corresponds to an average oxide layer thickness of 0.02 nm in dry air and 0.51 nm in wet air.