Control of temperature distribution to suppress macro-defects in solution growth of 4H-SiC crystals

•Surface damage caused before seeding and roughening by SiC particles were investigated.•Hillocks of 6H-SiC were formed on the seed surface before seeding by vaporized solvent.•The melt-back process completely removed the damaged layer before growth began.•Adhesion of SiC particles on the growth surface introduced surface roughening.•Adhesion of SiC particles was suppressed by control of carbon supersaturation. We investigated the surface roughening in 4H-SiC solution growth from the following two aspects: the roughening of the seed surface before seeding and the roughening caused by the adhesion of SiC particles during growth. First, we investigated the morphological changes of the seed surface before and after the melt-back process. The seed surface just before seeding was covered with macrosteps and 6H-SiC hillocks with a height of several micrometers. This surface roughening was caused by condensation of droplets of vaporized solvent on the seed surface. We found that the 6H-SiC hillocks were the origins of trench defects. The melt-back process completely removed the hillocks and produced a smooth surface adequate for successive bulk growth. Second, we investigated surface roughening caused by the formation of SiC particles. The adhesion of SiC particles on the growth surface introduced trench defects and polytype inclusions. The adhesion of SiC particles was suppressed by controlling the distribution of carbon supersaturation in the solvent.