We reported the effect of trimethylindium (TMIn) flow rate in the barrier layer on the structural and optical properties of InxGa1-xN/InyGa1-yN multiple quantum wells (MQWs) grown on (0001)-oriented sapphire substrates by low-pressure metalorganic chemical deposition (LP-MOCVD). It was found that the change of TMIn flow rate dramatically influences the interface quality and optical properties. Temperature-dependent photoluminescence (PL) and high-resolution X-ray diffraction (HRXRD) measurements provide proof evidence that the increment of TMIn flow rate deteriorates the interfacial abruptness, decreases the emission wavelength (blue shift) and the efficiency of nonradiative recombination process. (C) 2003 Elsevier B.V. All rights reserved.