InGaN multiple-quantum-well light-emitting diodes on an AIN/sapphire template by metalorganic chemical vapor deposition

An InGaN multiple-quantum-well (MQW) LED grown on AlN/sapphire template is reported. Comparing with the conventional LED on sapphire using a low temperature (LT) buffer layer, the LED on AlN/sapphire template shows better electrical and optical characteristics. The crystalline quality of the LED structure was investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The zeroth, -first- and -second-order satellite peaks and the Pendellosung fringes can be seen clearly in (0004) XRD omega/2theta rocking curves for the LED on AlN/sapphire template. While, for the LED on sapphire, only the zeroth and -first-order satellite peaks can be seen. The full width at half maximum (FWHM) of GaN in (0004) omega scan is about 82.8 and 231.6 aresec for the LED grown on AlN/sapphire template and sapphire, respectively. The dislocation density is 5 x 10(7)-3 x 10(8) cm(-2) for the LED on AlN/sapphire template and 2-5 x 10(9) cm(-2) for the LED on sapphire. The reverse leakage current of the LED on AlN/sapphire template is over one order of magnitude lower than that on sapphire due to the low threading dislocation density in the epilayer. The optical power of the LED on AlN/sapphire template increased sublinearly up to 300 mA injection current. (C) 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.