[15p-B401-1~18] 15.4 III-V-group nitride crystals

▲ [15p-B401-5] High crystallinity N-polar InGaN layers grown on ScAlMgO4 substrates cleaved along its c-plane

〇(DC)Pavel Sergeyevich Kirilenko¹, Mohammed Najmi¹, Bei Ma², Artem Shushanian¹, Martin Velazquez-Rizo¹, Daisuke Iida¹, Kazuhiro Ohkawa¹ (1.King Abdullah Univ. of Science and Technology, 2.Chiba Univ.)

Keywords: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 0.2^o 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].