The performance characteristics of AlGaN-based deep ultraviolet light emitting diodes (UV-LEDs) grown by metalorganic vapor phase epitaxy on sputtered and high temperature annealed AlN/sapphire templates are investigated and compared with LEDs grown on epitaxially laterally overgrown (ELO) AlN/sapphire. The structural and electro-optical properties of the devices on 350 nm sputtered and high temperature annealed AlN/sapphire show similar defect densities and output power levels as LEDs grown on low defect density ELO AlN/sapphire templates. After high temperature annealing of the 350 nm sputtered AlN, the full widths at half maximum of the (0002) and reflections of the high resolution x-ray diffraction rocking curves decrease by one order of magnitude to 65 arc sec and 240 arc sec, respectively. The curvature of the sputtered and HTA AlN/sapphire templates after regrowth with 400 nm MOVPE AlN is with −80 km−1 much lower than the curvature of the ELO AlN/sapphire template of −160 km−1. The on-wafer measured output powers of 268 nm LEDs grown on 350 nm sputtered and high temperature annealed AlN/sapphire templates and ELO AlN/sapphire templates were 0.70 mW and 0.72 mW at 20 mA, respectively (corresponding to an external quantum efficiency of 0.75% and 0.78%). These results show that sputtered and high temperature annealed AlN/sapphire provide a viable approach for the fabrication of efficient UVC-LEDs with reduced complexity and thus reduced costs.
AlGaN-based deep UV LEDs grown on sputtered and high temperature annealed AlN/sapphire
Norman Susilo, Sylvia Hagedorn, Dominik Jaeger, Hideto Miyake, Ute Zeimer, Christoph Reich, Bettina Neuschulz, Luca Sulmoni, Martin Guttmann, Frank Mehnke, Christian Kuhn, Tim Wernicke, Markus Weyers, Michael Kneissl; AlGaN-based deep UV LEDs grown on sputtered and high temperature annealed AlN/sapphire. Appl. Phys. Lett. 22 January 2018; 112 (4): 041110. https://doi.org/10.1063/1.5010265
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