Epitaxial lateral overgrowth (ELO) of GaN on SiO2-masked (0001) GaN substrates has been investigated by using chloride-based growth chemistries via hydride vapor phase epitaxy (HVPE) and metal organic vapor phase epitaxy (MOVPE). Diethyl gallium chloride, (C2H5)2GaCl, was used in as the MOVPE Ga precursor. The lateral and vertical growth rates as well as the overgrowth morphology of ELO GaN structures are dependent on growth temperature, V/III ratio and the in-plane orientation of the mask opening. A high growth temperature and low V/III ratio increase the lateral growth rate and produce ELO structures with a planar surface to the GaN prisms. High-quality coalesced and planar ELO GaN has been fabricated by both growth chemistries. The use of the diethyl gallium chloride source allows for the benefits of HVPE growth to be realized within the MOVPE growth environment.