GaN growth on Si(111) substrate typically routes to the initial high dislocation density and cracks because of the large discrepancy of lattice constant and thermal expansion coefficient between GaN and Si. This article reports the use of plasma-assisted molecular beam epitaxy (MBE) to grow crack-free InGaN on Si(111) substrate using an optimized GaN/AlN buffer layer. X-ray diffraction revealed that monocrystalline InGaN was obtained. To assess the morphology of the sample, scanning electron microscopy (SEM) and atomic force microscopy (AFM) have been employed. A layer-cracking problem was not observed in our samples. The root-mean-square (rms) roughness value of the surfaces sample is 10.34 nm on a 10 mu m x 10 mu m scan area. The film is then characterized by photoluminescence (PL) spectroscopy. PL measurement exhibits a sharp and intense band edge emission of InGaN with yellow luminescence (YL), red luminescence (RL) and near infrared luminescence (NIRL) peaks. To date, no approaches have been reported that YL is observed in samples grown by MBE. (C) Koninklijke Brill NV, Leiden, 2011