A method of suppressing parasitic particle formation in a metal organic chemical vapor deposition process is described. The method may include providing a substrate to a reaction chamber, and introducing an organometallic precursor, a particle suppression compound and at least a second precursor to the reaction chamber. The second precursor reacts with the organometallic precursor to form a nucleation layer on the substrate. Also, a method of suppressing parasitic particle formation during formation of a III-V nitride layer is described. The method includes introducing a group III metal containing precursor to a reaction chamber. The group III metal precursor may include a halogen. A hydrogen halide gas and a nitrogen containing gas are also introduced to the reaction chamber. The nitrogen containing gas reacts with the group III metal precursor to form the III-V nitride layer on the substrate.