Improvement in Output Power of 280-nm Deep Ultraviolet Light-Emitting Diode by Using AlGaN Multi Quantum Wells

We fabricated high-output-power 280-nm light-emitting diodes (LEDs) by employing high-crystal-quality AlN templates and optimized epitaxial structures. The emission wavelength, output power, forward voltage, spectral linewidth, and external quantum efficiency of the fabricated device measured at 20 mA were 281.0 nm, 2.45 mW, 7.53 V, 10.6 nm, and 2.78%, respectively. In the case of DC operation, the output power increased with time probably resulting from enhanced p-type activation by junction heating. We also fabricated a multi-chip device which consisted of 26 small-chip LEDs. It produced 223 mW at a pulse injection current of 1850 mA. (C) 2010 The Japan Society of Applied Physics