Red Emission of InGaN/GaN Multiple-Quantum-Well Light-Emitting Diode Structures with Indium-Rich Clusters

The authors present the growth of InGaN/GaN multiple-quantum-well (MQW) light-emitting diode (LED) structures, which show red emission. Transmission electron microscopy analyses proved that shell-like and quantum-dot-like (QD-like) clusters are formed in the initial four InGaN quantum well layers due in part to the lattice mismatch. The introduction of dislocations near the interfaces and interiors of MQWs induced high indium compositions in the InGaN quantum well layers. The room temperature photoluminescence (PL) measurement shows that the structure can emit the green to red broad spectral luminesce with major and minor peaks at 630 and 550 nm due to fluctuation of indium compositions in MQWs. In an electroluminescence (EL) spectrum measurement, the red emissions are blue shifted in the wavelength range from 630 to 609 nm with an increase of the injected currents from 5 to 100 mA.