Highly Efficient InGaN-Based 383-nm Ultraviolet Light-Emitting Diodes Fabricated on Sapphire Substrate Using High-Temperature-Grown AlN Buffer

Highly efficient 383-nm ultraviolet light-emitting diodes (UV-LEDs) were fabricated on high-quality GaN formed on sapphire using high-temperature-grown AlN buffer. Photoluminescence intensity for the multiple-quantum-well active layers was almost constant for wavelength longer than 380 nm, suggesting the high emission efficiency. For conventional flip-chip LEDs, output power, operation voltage, and external quantum efficiency at 20 mA were 23 mW, 3.5 V, and 36%, respectively. The internal quantum efficiency was estimated to be as high as 72%. To the best of our knowledge, this efficiency was the highest value reported for UV-LEDs formed on sapphire. These values were comparable to those for visible LEDs.