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The crystallinity and morphology of single-crystal 3C-SiC homoepilayers grown on heteroepilayer (0 0 1) substrates by low-pressure chemical vapor deposition were investigated. The crystalline qualities of homoepilayers were critically dependent upon the defects of heteroepilayer substrates because planar defects, predominantly stacking faults and twins, and protrusions existing on the heteroepilayer surface propagated into the homoepilayers. A surface etching process using reactive ion etching (RIE) of the backside of free-standing heteroepilayers, the interface with Si substrates, was proposed to minimize the defect densities on the heteroepilayer surface. Analyses of high resolution X-ray diffraction (HRXRD) and atomic force microscope (AFM) reveal that simultaneous reductions of both surface roughness and defect densities on the heteroepilayer surface are achieved by an etching depth of 4 μm. Cross-sectional scanning electron microscopy (SEM) observation clearly shows that protrusions on the RIE-treated heteroepilayer surface are readily buried by growing homoepilayers. Furthermore, the results of cross-sectional transmission electron microscopy (XTEM) indicate that (i) significant amounts of planar defects are removed by the RIE process of the backside of heteroepilayers and (ii) most of planar defects propagating into the homoepilayers are terminated by coalescences between one another during early homoepitaxial growth stages.

Single-crystal 3C-SiC epilayers were grown on on-axis Si(0 0 1) substrates by low-pressure chemical vapor deposition. The dependence of the densities of stacking faults and twins on epilayer thicknesses and growth conditions—including the reactor pressure, the substrate temperature, and the inlet gaseous composition—were investigated by a series of experiments and simulations. Simple indexes were developed to predict the planar defect densities in terms of the flux ratio of adatoms on the deposition surface. The planar defect densities were significantly reduced with increasing the epilayer thickness until continuous surfaces with {1 0 0} planes were formed at 0.7 μm. The stacking fault density was a function of the surface flux ratio of carbon adatom to atomic hydrogen, while the twin density was a function of that of silicon adatom to atomic hydrogen. Those densities were decreased almost linearly with increases in the surface flux of atomic hydrogen at fixed flux values of carbon and silicon adatoms. The surface flux of atomic hydrogen was increased as either the reactor pressure was decreased or the substrate temperature was increased.

A series of low-pressure chemical vapor deposition experiments and gas-surface chemical kinetic simulations have been carried out to achieve significant reductions of twin and protrusion in 3C-SiC heteroepitaxial growth on Si(1 0 0) substrates. A two-step epitaxial process, consisting of a nucleation stage and a subsequent epitaxial stage, was newly proposed by comparisons between experimental results and numerical predictions. The twin formation was successfully suppressed under the growth conditions of the nucleation stage leading to a relative flux ratio of C to Si larger than 56 on the deposition surface. The surface protrusion density was decreased from 7.5×10 6 to 6.5×10 4 cm −2 when the conventional carbonization process was replaced with the proposed nucleation stage.