Prospects of the use of liquid phase techniques for the growth of bulk silicon carbide crystals

The perspectives of SiC liquid phase crystallization (solution growth) were studied in respect of its applicability as manufacturing method of SIC bulk crystals. SiC phase diagram and solubility data of carbon in Si-containing binary and ternary liquid alloys were reviewed. Models of growth stability are applied to predict feasible crystallization rates and crystal diameters without the formation of parasitic phases (e.g. inclusions). The growth limiting factors, mass transport and kinetics have been analyzed giving growth rates comparable to SIC vapor growth (0.1...1 mm h(-1)). From these considerations a specific reactor has been designed and realized which allows SiC growth from Si-solution at high temperatures (T less than or equal to 2300 degrees C) and high pressures (T less than or equal to 200 bar) under defined mass transfer control. Single crystalline SIC was prepared from Si:C solution at temperatures of 1800-2000 degrees C. The growth rate was found to range between 0.05 and 0.2 mm h(-1). Crystal quality was analyzed, e.g. by X-ray diffractometry and photoluminescence showing good crystalline properties and indications for a low content of residual impurities, respectively. The closing/annihilation of micropipes during liquid phase crystallization was observed and could be reproduced. For the first time solution growth of bulk SiC with a 1.4 " diameter could be successfully demonstrated. In summary, liquid phase growth from solution can be considered as promising method to grow low defect SIC bulk material although its development to an industrial process represents a challenge in materials science and crystal growth technology. (C) 1999 Elsevier Science S.A. All rights reserved.