Oriented specimens Oxidation

It must be noted that most studies on metal-doped TiCh are oriented toward the photo-oxidation of environmental pollutants (e.g., 4-nitrophenol,299 4-chloro-phenol300) rather than toward the photoelectrolysis of water (but see Section 6.4 of this Chapter). Other aspects of metal doping include the effect of UV radiation of Ag-doped Ti02 specimens,301 302 plasma treatment,303 and thermal treatment.304 Metal doping by ion implantation of I1O2 has been discussed.91,305... 

In the comparison of ferroelectric or ferromagnetic systems as suitable for testing nucleation theory it is clear that the latter have several disadvantages. For example, in the case of ferromagnetics domains are only visible at the specimen surface. If they are transparent, then they are difficult oxides to produce. Furthermore, their low magnetostriction relative to ferroelectrics makes their boundaries less visible and their orientation freedom greater. Each different orientation is analogous to a different phase and the inherent simplicity of the system is thereby reduced. 

A commercial 4H-SiC (0001) wafer was used as a specimen. A gas mixture of helium, carbon tetrafluoride and oxygen was used as the reactive gas. Table 19.1 shows the removal rates of both Si- and C faces of the SiC wafer under various experimental conditions. We achieved a high removal rate of 4 gm/min for the Si face and 8 gm/min for the C face. It is shown that the removal rates of the C face are higher than those of the Si face. In most cases, the former are twice the latter. Generally, the oxidative rate of SiC varies with the SiC surface orientation, and the C face is oxidized more rapidly than the Si face. Thus, there is a possibility that oxidation plays a prominent role in the etching of SiC. 

---