InGaN/GaN multiple quantum well light emitting diodes with charge asymmetric resonance tunneling structure, which can emit dual color lights of blue/green or blue/yellow, were grown on sapphire by metalorganic chemical vapor deposition. Their optical and structural properties are studied by high-resolution X-ray diffraction, high-resolution transmission electron microscopy, temperature-dependent photoluminescence (PL) and photoluminescence excitation (PLE). PL peak shifts and PLE features are found to vary with the well-growth temperature. The luminescence mechanism is discussed in details, correlating to the In composition fluctuation, carrier localization and the quantum confined Stark effect. (C) 2012 Elsevier B.V. All rights reserved.