Electroluminescence properties of Eu-doped GaN-based red light-emitting diode by OMVPE

We investigated the electroluminescence (EL) properties of europium (Eu)-doped GaN-based red light emitting diode (LED). Under current injection, the energy transfer from the GaN host material to Eu3+ ions successfully occurred and the red emission from Eu3+ ions was observed with naked eyes under normal lighting conditions at room temperature (RT). The operation voltage was as low as 2.4 V. The dominant peak was observed at a wavelength of 621 nm and its intensity increased with increasing applied voltage. The several peaks beside the main peak appeared with higher injected currents in the EL spectrum. The light output power, which was integrated over the main peak, as a function of injected current shows the saturated behaviour in the high injected current region. As a result, the external quantum efficiency was still lower than the conventional GaN-based blue and green LEDs at high injected current. However, this result suggests a novel way to realize GaN-based red LEDs, which leads to realize a monolithic device composed of red, green and blue GaN-based LEDs for full-colour display or lighting technology. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim