Effect of Morphology and Current Density on the Electrochemical Behavior of Graphite Electrodes in PC-Based Electrolyte Containing VEC Additive

A relatively comprehensive analysis of the problem of seed graphitization during seeded sublimation growth of SiC bulk crystal is presented in the paper. It is shown that an intentional thermal etching process for the seed can cause serious seed graphitization due to preferential loss of Si from the seed. A polycrystalline deposit will be formed on the seed after growth if serious seed graphitization occurs. In the case of slight graphitization of the seed, the presence of additional carbon on the seed will act as impurities, making the growth more difficult and even inducing defect formation. Besides, additional carbon can be incorporated into SiC. Two possible mechanisms for this are proposed in the paper. It is suggested to initiate the growth with a relatively low growth rate in order to incorporate additional carbon into SiC as much as possible. Since the main cause for seed graphitization is the preferential loss of Si from the seed, maintaining a high Si pressure near the seed could be a possible solution to avoid seed graphitization. The problem of maintaining a high Si pressure near the seed is discussed in the paper. (C) 2003 Elsevier B.V. All rights reserved.

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