Oxide-Assisted Growth Mechanism

The distribution of shapes, sizes, and growth directions ofSiNWs [54]. 

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Oxide-Assisted Growth of Silicon and Related Nanowires Growth Mechanism, Structure and Properties... 

Many SiCNWs formation mechanisms such as vapor-solid mechanism (VS), vapor-liquid-solid mechanism (VLS) and oxide-assist growth (OAG) have been proposed. It is needed to clarify the formation mechanism of SiCNWs synthesized by thermal evaporation method for improvement of the product quantity, which leads to the sufficient amount of SiCNWs for the application researches. Various chemical reactions have been discussed but there are no experimental results about exhaust gas from the SiCNWs production system and no direct observation of the formation of SiCNWs. 

Since the paper by Pilling and Bedworth in 1923 much has been written about the mechanism and laws of growth of oxides on metals. These studies have greatly assisted the understanding of high-temperature oxidation, and the mathematical rate laws deduced in some cases make possible useful quantitative predictions. With alloy steels the oxide scales have a complex structure chromium steels owe much of their oxidation resistance to the presence of chromium oxide in the inner scale layer. Other elements can act in the same way, but it is their chromium content which in the main establishes the oxidation resistance of most heat-resisting steels. 

Results obtained for the oxide film on bismuth illustrate this approach [29]. The oxide grows by the field-assisted migration of ions and Fig. 12 shows that the forward sweep of a cyclic voltammogram exhibits the plateau currrent characteristic of this mechanism. On the reverse sweep, where the field is insufficient to sustain further film growth, the current falls to zero until the potential is reached at which the film is reduced. The figure also shows the photocurrent observed under the same conditions when the electrode is illuminated. On the forward sweep, the photocurrent rises as the film thickens, but on the reverse sweep it falls and then changes sign before the reduction potential is reached. 

The generally accepted model for passive film growth, illustrated in Fig. 3-14, is of field-assisted film formation, which is essentially a modified Cabrera-Mott model originally established for gaseous oxidation and the formation of thin oxide films in a gas at low temperature (Cabrera and Mott, 1948-1949 Fehlner and Mott, 1970). This classical theory describes the growth, in the direction perpendicular to the surface, of an oxide layer completely covering the substrate surface, by a hopping mechanism. The... 

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