Improvement in the growth rate of cubic silicon carbide bulk single crystals grown by the sublimation method

Abstract

Silicon carbide (SiC) is a valuable electronic material for high-temperature and high-power applications. The two most studied forms of SiC are the 6H and 3C-SiC polytypes. Cubic SiC is attractive because of the high low field mobility and the zincblende crystal structure. Presently, 3C-SiC is usually produced using chemical vapor deposition CVD techniques on silicon substrates. Because of a large lattice mismatch (∼ 20%), the quality of the CVD films is low, and therefore, several investigators have tried to produce bulk 3C-SiC using sublimation technology. We have investigated the growth of 3C-SiC in close space environment. Utilizing this geometry, we have been able to obtain growth rates in excess of 251 μm/h by optimizing source powder height, temperature gradient, seed temperature and system pressure. The seed crystals utilized for this study were off-axis (1 0 0) 3C-SiC films grown on Si substrates (substrates removed prior to growth). On these substrates a clear yellow 3C-SiC material was grown. Etch results indicate a lower density of stacking faults (by at least three orders of magnitude) for the bulk crystals. Additionally, second generation growths using sublimation bulk crystals as substrate material were investigated.