Characterization Of Asymmetric Gan/Ingan Multiple Quantum Well

The microstructure and electronic structure of the asymmetric GaN/InGaN multiple quantum well (MQW) light emitting diodes are characterized by transmission electron microscope (TEM), cathodoluminescence (CL) and capacitance-voltage (C-V) measurements. In TEM images, the asymmetric structure of InGaN/GaN MQW are observed as designed with different width of QWs and barriers, and indium content in QWs as well. In high-resolution TEM images, the InGaN quantum wells and GaN barriers show the same lattice constant, and some degradation can be seen at the bottom of each InGaN QW. There are two emission peaks, 450 and 530 nm in CL spectrum, similar to the ones in electroluminescence spectrum. The double emission peaks are assigned to the irradiative recombination in different InGaN QWs. From the C-V data, the apparent carrier concentration in the asymmetric MQW is calculated. There are five obvious peaks which are well explained by an energy band scheme of InGaN/GaN MQW. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim