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▲ [15p-B401-5] High crystallinity N-polar InGaN layers grown on ScAlMgO4 substrates cleaved along its c-plane
キーワード：InGaN growth, ScAlMgO4, High crystallinity
Here, we report successful growth of high-crystallinity InGaN layers on ScAlMgO4 (SAM) substrates using metalorganic vapor-phase epitaxy. Utilizing SAM substrate’s cleavability along its c-plane, we have prepared atomically flat surface for the InGaN growth. The InGaN layer was grown directly, without any low-temperature buffer layer. The resulting film has thickness of approximately 200 nm and a distinctive hexagonal hillock morphology, which was linked to the film’s N-polarity in the previous work of our group[1]. Using inductively coupled plasma-optical emission spectroscopy, In/(In+Ga) ratio was found to be 17%, which corresponds to the InGaN lattice match with a SAM substrate[2].
Figure 1 shows the InGaN layer characterization using X-ray diffractometer. There, the improvement of the InGaN crystalline quality correlates with the usage of the cleaved SAM substrate, in comparison to as-received substrate, which was polished with 0.2o offset towards m-plane. The calculated threading dislocation densities in the case of sliced SAM substrate are as low as 2.9 × 108 cm–2 and 1.6 × 109 cm–2 in the case of screw-type and edge-type dislocations. Such TD densities are more than one order smaller than in the results of other research groups for InGaN on SAM substrate with similar In content[2,3].
Figure 1 shows the InGaN layer characterization using X-ray diffractometer. There, the improvement of the InGaN crystalline quality correlates with the usage of the cleaved SAM substrate, in comparison to as-received substrate, which was polished with 0.2o offset towards m-plane. The calculated threading dislocation densities in the case of sliced SAM substrate are as low as 2.9 × 108 cm–2 and 1.6 × 109 cm–2 in the case of screw-type and edge-type dislocations. Such TD densities are more than one order smaller than in the results of other research groups for InGaN on SAM substrate with similar In content[2,3].