AlInN alloys are promising as cladding layers in GaN-based visible laser diodes (LDs) because they show a large index contrast to GaN or InGaN in whole visible wavelengths at an alloy composition lattice-matched to GaN. To consider the application to cladding layers in LDs, a sufficiently-thick film with a smooth surface is necessary. In this study, therefore, we grew 300-nm-thick AlInN films with various alloy compositions on a c-plane GaN/sapphire template or a free-standing (FS) GaN substrate by metalorganic chemical vapor deposition (MOCVD). The results showed that no lattice relaxation occurred for samples with InN molar fractions from 0.144 to 0.197, and the InAlN films with low InN molar fractions showed a relative smooth surface. However, it turned into a granular surface morphology resulting from a columnar polycrystalline structure when the InN molar fraction exceeded a compositional boundary of in-plane lattice matching. Eventually, it was confirmed that epitaxial AlInN films with a good crystal quality and smooth surface roughness were grown at alloy compositions almost perfectly lattice-matched to GaN/sapphire and FS-GaN. As for the smooth-surface AlInN single-layers, the optical constants as well as energy bandgaps were determined. On the day in the conference, we would like to present new proposals for applications of the high-quality AlInN films to components in devices other than cladding layers in LDs.

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Makoto Miyoshi, Mizuki Yamanaka, Takashi Egawa, and Tetsuya Takeuchi, "Epitaxial growth of high-quality AlInN thick films and its device applications (Conference Presentation)," Proc. SPIE 10940, Light-Emitting Devices, Materials, and Applications, 109400X (Presented at SPIE OPTO: February 06, 2019; Published: 4 March 2019); https://doi.org/10.1117/12.2506760.6009915511001.