High performance AlGaInN ultraviolet light-emitting diode at the 340 nm wavelength

We report on high output power from the quaternary AlGaInN multiple quantum well (MQW) ultraviolet light emitting diodes (UV LEDs) in the 340 nm wavelength range. The output power up to 1.5 mW from a 100mum diameter device with bare-chip configuration was measured under room temperature cw operation. The internal quantum efficiency was estimated to be between 7 and 10%. In addition, the output power and external quantum efficiency for fully packaged 1 x 1 mm(2) large area device were as high as 54.6 mW and 1.45%, respectively, at the injection current of 200 A/cm(2) under pulsed operation. The devices were incorporated into prototype system for fluorescence based bio-sensing as excitation source.