IN-SITU INFRARED STUDY OF SURFACE OXIDE FORMATION ON GAS-EVAPORATED SI MICROCRYSTALS

Infrared absorption of gas-evaporated Si microcrystals has been measured in situ. The spectra showed an absorption band attributable to the Si-O-Si stretching vibration, thereby demonstrating the formation of surface oxides in the evaporation chamber. The present in situ measurements further revealed the formation of various Si-H bonding groups which could not be clearly observed in the samples exposed to air. The surface oxide layers containing Si-H bonding groups are thought to grow during the gas-evaporation process through the reaction of evaporated Si atoms with residual O2, H-2 and H2O molecules. The evolution of the oxide to form native oxide layers was also studied by monitoring the changes in absorption spectra upon exposure to air. It was found that the oxidation of the Si microcrystals proceeds much more slowly than in Si wafers.