263 nm wavelength UV-C LED on face-to-face annealed sputter-deposited AlN with low screw- and mixed-type dislocation densities

Abstract Regarding deep-ultraviolet optical device applications, face-to-face annealed sputter-deposited AlN (FFA Sp-AlN) is a promising alternative to the conventional metalorganic vapor phase epitaxy (MOVPE)-prepared templates on sapphire substrates. However, FFA Sp-AlN tends exhibit AlGaN growth-related hillock generation and surface morphology deterioration. In this study, we optimized sputter-deposition conditions for MOVPE growth respectively reduce density size. After confirming surface-flattening, fabricated 263 nm wavelength UV-C LEDs achieved maximum external quantum efficiencies of approximately 4.9% 8.0% without with silicone encapsulation, respectively.