By Mg pretreatment of the bottom GaN barrier surface,the growth behavior of the high indium content InGaN/GaN quantum wells(QWs)changed greatly;the interface quality and luminescence capability were significantly improved.Without Mg pretreatment,spiral growth dominated;lateral fluctuation of indium content and QW thickness,lack of interface abruptness,and formation of In-rich regions were evident within the InGaN layer.With Mg pretreatment the InGaN layer was of homogeneous indium distribution and abrupt interfaces as investigated by X-ray diffraction and scanning transmission electron microscopy.The luminescence properties were investigated by photoluminescence,cathodoluminescence and electroluminescence(EL)measurements,and further analyzed by energy band structures of various InxGa1-xN/GaN QWs.Enhanced light emission from the Mg pretreated InGaN layer was achieved and attributed to the improvement of interface quality,reduction of polarization field and suppression of nonradiative recombination at dislocation pits.