High crystallinity N-polar InGaN layers grown on cleaved ScAlMgO4 substrates

We have grown high-crystallinity InGaN layers on ScAlMgO4 (SAM) substrates using metalorganic vapor-phase epitaxy. We have prepared atomically flat SAM substrates by cleaving them along the c-plane and have utilized direct InGaN growth without any low-temperature buffer layer. The resulting InGaN layer has a distinct hexagonal hillock morphology and remarkable crystalline quality. The x-ray rocking curve measurements showed that (0002̄) and (10–1–2) peaks full widths at half-maximum are as good as 384 and 481 arcsec, respectively. The calculated threading dislocations densities are as low as 2.9 × 108 and 1.6 × 109 cm−2 in the case of screw-type and edge-type dislocations, respectively.