  We present the effect of miscut angle of SiC substrates on N-polar AlN
growth. The N-polar AlN layers were grown on C-face 4H-SiC substrates with a
miscut towards <-1100> by metal-organic vapor phase epitaxy (MOVPE). The
optimal V/III ratios for high-quality AlN growth on 1 deg and 4 deg miscut
substrates were found to be 20000 and 1000, respectively. MOVPE grown N-polar
AlN layer without hexagonal hillocks or step bunching was achieved using a
4H-SiC substrate with an intentional miscut of 1 deg towards <-1100>. The
200-nm-thick AlN layer exhibited X-ray rocking curve full width half maximums
of 203 arcsec and 389 arcsec for (002) and (102) reflections, respectively. The
root mean square roughness was 0.43 nm for a 2 um x 2 um atomic force
microscope scan.
