Advances of AlGaN-based high-efficiency deep-UV LEDs

Abstract

We demonstrated AlGaN-based multi-quantum-well (MQW) deep-ultraviolet (UV) light-emitting diodes (LEDs) with wavelengths in the range of 222–351 nm, fabricated on low threading dislocation density (TDD) AlN template on sapphire. A high internal quantum efficiency (IQE) of 50–80% was achieved from AlGaN or quaternary InAlGaN MQWs by fabricating them on low TDD AlN templates. Also, an electron injection efficiency (EIE) was markedly improved by using multi-quantum barrier (MQB). Over 20 mW cw output power was obtained for 256–275 nm LEDs, which will be useful for sterilization applications. The maximum external quantum efficiencies (EQEs) were 1.8 and 2.75% for 247 and 270 nm AlGaN-LEDs, respectively.