Photoluminescence (PL) efficiency enhancement produced by deposition of Ag/SiO2 core/shell nanoparticles (NPs) on the GaN/InGaN multi-quantum well structure was studied as a function of quantum well (QW) number in the structure. For back-surface laser excitation the strongest PL enhancement by 1.5 times was observed for single QW structure, the weakest for the 5QW structure. The result is ascribed to Ag/SiO2 NPs localized surface plasmons coupling to the MQW region and the dependence of the coupling efficiency on the distance to the NP layer. Simple modeling suggests that the coupling efficiency starts to decrease for distances higher than about 50 nm. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.097205jes] All rights reserved.