Variations of macrostep structures with solvent compositions in 4H-SiC solution growth

Abstract

  We have reported changes in macrostep structure by various additives in solution growth of 4H-SiC. Typically, solution growth exhibits severe step-bunching that developed large macrosteps in micrometers height. The large macrosteps result in trench-like defects accompanying solvent inclusions. In contrast, Al addition drastically improved surface smoothness by reducing average macrostep height. We have shown that some additives, such as Sc and Sn, also improve surface smoothness, in addition to Al. These results demonstrate that the surface modification by additives is useful to control surface morphology in solution growth. Based on the studies on wetting properties and surface tensions of various solvents, we have shown that the interfacial energy in the 4H-SiC/solvent interface increased by the additives that tend to decrease the macrostep height. We suppose that, owing to the increase in the interfacial energy, reduction of the frequency of 2D nucleation helps to sustain a flat growth surface covered by smooth step-flow patterns.