Reduction of dislocation density in lattice-relaxed Al<sub>0.68</sub>Ga<sub>0.32</sub>N film grown on periodical 1 μm spacing AlN pillar concave-convex patterns and its effect on the performance of UV-B laser diodes
Tomoya Omori, Ayumu Yabutani, Shunya Tanaka, Kazuki Yamada, Moe Shimokawa, Ryota Hasegawa, Sho Iwayama, Hideto Miyake, Tetsuya Takeuchi, Satoshi Kamiyama, Motoaki Iwaya
Abstract
Abstract We report the results of crystal growth of thick AlGaN films on periodical 1 μ m spacing AlN pillar concave-convex patterns and their impact on the performance of UV-B laser diodes. The formation of voids in the AlGaN film by increasing the AlN pillar height and the use of high-quality AlN templates were effective in improving the quality of AlGaN, and the dislocation density in the AlGaN film was reduced to approximately 3.4 × 10 8 cm −2 . A UV-B laser diode was fabricated on the optimized AlGaN, demonstrating a threshold current density of ∼12 kA cm −2 and a high yield rate of over 90%.