AlGaN-Based 355 nm UV Light-Emitting Diodes with High Power Efficiency

High-efficiency AlGaN-based 355 nm UV light-emitting diodes (LEDs) grown on low-dislocation-density AlGaN/sapphire templates are reported. Flip-chip-mounted mesa LEDs exhibit an output power of 9.8 mW (22.7 mW) at a DC current of 40 mA (100 mA), corresponding to an external quantum efficiency of 7% at 40 mA. Due to the low forward voltage of only 3.8 V at 40 mA, this translates into a power efficiency of 6.5% at 40 mA. These performance data have been achieved under optimized growth conditions for the low-In-content (AlGaIn)N single quantum well and a reduced thickness of the absorbing p-GaN top layer.