Development of 230–270 nm AlGaN‐based deep‐UV LEDs

We demonstrated AlGaN multi‐quantum well (MQW) deep‐ultraviolet (UV) light‐emitting diodes (LEDs) with wavelengths in the range of 227.5 to 273 nm fabricated on high‐quality AlN buffers on sapphire substrates grown by metal‐organic chemical vapor deposition (MOCVD). We realized crack‐free, thick AlN buffers on sapphire with a low threading dislocation density (TDD) and an atomically flat surface by using the ammonia (NH3) pulse‐flow multilayer (ML) growth technique. We obtained single‐peaked operation of an AlGaN‐MQW LED with a wavelength of 227.5 nm, which is the shortest wavelength of AlGaN‐based LED on sapphire. The maximum output power and the external quantum efficiency (EQE) of the 261‐ and 227.5‐nm LEDs were 1.65 mW and 0.23% in room‐temperature (RT) continuous‐wave (CW) operation, and 0.15 mW and 0.2% in RT pulsed operation, respectively.