Comparative oxidation studies of SiC(0001̄) and SiC(0001) surfaces

Abstract

A comparison of the kinetics of oxidation at 995 and 1345 K of the SiC(0001̄) and SiC(0001) crystal faces is made. The oxidation rate on the SiC(0001̄) (C-rich face) is higher at both temperatures. SiO2 is formed. At 1345 K, the initial oxidation process is retarded by excess surface carbon. When the excess carbon is volatilized by either CO or CO2 formation, the oxidation rate is higher at 1345 K than at 995 K.

Porous SiC Preparation, Characterization and Morphology

“…The clear difference between the Si-face and C-face I-V curves confirms the dissimilar interface junction properties of the two crystalline faces in a photoelectrochemical process. The larger current density on the C-face provides a faster electrochemical etching rate or oxidation rate than the rate on the Si-face, which is in agreement with the result from wet oxidation experiments [23]. Moreover, the ratio of the porous layer thickness in EXP.…”

“…The oxidation of a Si-terminated surface proceeds at a much slower rate. Although the oxidation chemistry in aqueous environment is likely somewhat different from that reported in Muelhoff et al [23], in which dry oxygen was used, the rate of oxidation for the (0001) surface is still larger by at least a factor of two than that of the (0001) surface when water vapor is used for oxidation. Consequently, the pore shape in a SiC crystal is greatly affected by the surface polarity.…”

“…To achieve controllable columnar pore growth, electrochemical etching should be done on 'non-etch stop' faces. The fact that the C-face oxidizes much faster than the Si-face in wet oxidation [23] suggests that in another kind of oxidation -the photo-electrochemical etching process -the C-face is less likely to be an etch stop than the Si-face. This suggests that etching the C-face of a SiC crystal may favor the columnar pore formation.…”

“…The basis for this statement depends upon experiments on the oxidation of the Si-and C-faces of SiC, in which the polar character of the silicon-carbon bond [22] was first suggested to be responsible. Muelhoff et al [23] reported different oxidation rates for (0001) and (0001), i.e. Si-rich and C-rich, surfaces for thermally oxidized SiC.…”

An assessment of the methods for determining defect or failure fractions in HTGR coated particle fuels and their relationship to particle microstructure

“…(2-1) has the value 0.52. Thus, if the oxide layer formed is lb.0 nm thick, a 4.8-nm (Muehlhoff et al 1986). Thereafter, at the lower temperature, the thickness of the oxide layer increases, if at all, only very slowly on the time scale of the initial oxide layer formation; at the higher temperature, the thickness of the oxide layer continues to increase but at a declining rate.…”