Step Arrays on Vicinal SiC Formed by Hydrogen-Etching

SiC is a useful substrate for heteroepitaxy, with step arrays on the surface used to minimize defects in the film [1]. We have studied the formation of steps on SiC surfaces using H-etching at 1600\r{ }C. Both Si-face, (0001), and C-face, (000\underline {1}), surfaces are used, with miscut angles of 0, 3.5\r{ }, and 12\r{ } towards $<$1\underline {1}00$>$ or $<$11\underline {2}0$>$ directions. For H-etched surfaces it is known that steps tend to form with full unit-cell height (1.5 nm for 6H-SiC) and with step edges perpendicular to $<$1\underline {1}00$>$ [2]. Accordingly, we find that miscuts towards $<$1\underline {1}00$>$ result in ordered arrays of steps. On the Si-face step bunching is observed, with typical step heights of 4.5 nm for 12\r{ } miscut. In contrast, for the C-face, little step bunching is observed, with the surface forming well ordered arrays of single-unit-cell-high steps. For the case of miscut towards $<$11\underline {2}0$>$ the situation is more complicated, with meandering steps observed. We conclude that the C-face is most ideal as a vicinal template. Supported by NSF. \newline [1] C.D. Lee et al. MIJ-NSR \textbf{7}, 2 (2002). \newline [2] V. Ramachandran et al. JEM \textbf{27}, 308 (1998).