AlGaN multiple-quantum-well-based, deep ultraviolet light-emitting diodes with significantly reduced long-wave emission

Abstract
We report on a deep UV light-emitting diode over sapphire substrate with AlGaN multiple-quantum-well active region. Pulsed atomic-layer epitaxy deposited low-defect AlN/AlGaN buffers and an optimized active layer design yielded a sharp quantum-well emission peak at 287 nm and very little long-wave secondary emission. For a 100 μm×100 μm unpackaged device, a power of 27 μW at 20 mA dc and a peak external quantum efficiency of 0.1% at 100 mA pulse pumping were measured. Flip-chip packaging should increase these numbers nearly by a factor of 3.