Dual wavelength InGaN/GaN multi-quantum well LEDs grown by metalorganic vapor phase epitaxy

InGaN/GaN multiple quantum well (MQW) light-emitting diodes (LEDs) with different well widths and barrier widths were grown on sapphire substrates using metalorganic vapor phase epitaxy (MOVPE). The designed emission wavelengths were in the blue and green regions. The blue MQWs and green MQWs were deposited sequentially and the growth parameters were separately optimized for single color blue and green emission LEDs. Room-temperature photoluminescence (PL) spectra of the dual wavelength samples under high-intensity laser excitation showed dual emission peaks. Electroluminescence (EL) of fabricated LEDs at the typical driving current of 20 mA was predominantly single color, depending on the sequence and the number of blue and green MQWs. The second emission could be enhanced with larger driving current and the relative intensity of the two emission peaks could thus be tuned. Total optical power of more than 7 mW was obtained from an unpackaged 300 mum die when over driven. (C) 2004 Elsevier B.V. All rights reserved.