Hydrogen Analysis by Using of Secondary Ion Mass Spectroscopy

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(1) Hydrogen analysisHydrogen analysis by using of secondary ion mass spectroscopy (SIMS) was carried out for the standard sample (SiO_2 on silicon) in which proton was implanted, and the optimum analytical conditions for hydrogen analysis were clarified. It is important for hydrogen analysis to control the raster size of an ion beam, neutralization, signal gating and so on.(2) Wet oxidation rateWet oxidation rates of chemically-vapor-deposited silicon carbide (CVD-SiC) and silicon nitride (CVD-Si_3N_4) were measured by a thermogravimetric technique. The oxidation films were analyzed by XRD and Raman spectroscopy. The oxidation rate was increased with increasing of water vapor pressure and decreasing of oxygen pressure in the atmosphere. This may be lead by the change of micro-defects in the oxide film (silica). Water vapor in the atmosphere accelerated the crystallization of oxide film at lower-temperatures (around 1373 K) and non-crystallization at higher-temperatures (>1873 K). It was clarified by laser Raman spectroscopy that amorphous silica was at around oxide/gas interface and cristobalite was at around oxide/ceramics interface, i.e., the oxide film formed was a duplex one. These results suggested that the formation of amorphous silica lowered the oxidation resistance of siliconbased ceramics for wet oxidation.