222 nm Deep-Ultraviolet AlGaN Quantum Well Light-Emitting Diode with Vertical Emission Properties

We demonstrated a 222 nm deep-ultraviolet (DUV) AlGaN multi-quantum well (MQW) light-emitting diode (LED) fabricated on a high-quality AlN buffer layer grown on a sapphire substrate, which is the shortest wavelength AlGaN LED ever reported. The maximum output power and the external quantum efficiency of the 222 nm AlGaN LED were 14 mu W and 0.003%, respectively, under pulsed current injection. We also investigated the radiation angle dependence of a series of 222-253 nm AlGaN QW DUV LEDs, and demonstrated that vertical c-axis emission can be obtained even when the Al composition of the AlGaN QW is as high as 83%. (C) 2010 The Japan Society of Applied Physics