MOVPE growth of N-polar AlN on 4H-SiC: Effect of substrate miscut on layer quality

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 〈1¯100〉 by metal-organic vapor phase epitaxy (MOVPE). The optimal V/III ratios for high-quality AlN growth on 1° and 4° miscut substrates were found to be 20,000 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° towards 〈1¯100〉. The 200-nm-thick AlN layer exhibited X-ray rocking curve full width half maximums of 203 arcsec and 389 arcsec for (0 0 2) and (1 0 2) reflections, respectively. The root mean square roughness was 0.4 nm for a 2 μm×2μm atomic force microscope scan.