In this study, the effects of trimethylindium (TMIn) treatment on the optical properties of InGaN/GaN multiple quantum wells with green emission were investigated. With TMIn treatment, InGaN decomposition, indium aggregation, and indium diffusion into the barrier region were suppressed such that more homogeneous indium composition and lower defect density lead to stronger and more uniform luminescence. It benefits the fabrication process and device design that TMIn treatment only enhances the luminescence intensity while changing the luminescence peak position (CIE coordinate) only a little. The research results provide important information to optimize the performance of green LEDs. (C) 2011 Elsevier B.V. All rights reserved.