Monocrystalline discrete and coalesced films of lateral- and pendeo-epitaxial GaN layers originating from stripes deposited within windows contained in SiO2 masks or from side walls of seed structures topped with silicon nitride masks have been grown via organometallic vapor phase deposition using on-axis GaN/AlN/6H-SiC(0001) substrates. Scanning and transmission electron microscopies and atomic force microscopy revealed (1) coalescence of the laterally growing layers, (2) a low density of dislocations in the overgrown regions, and (3) an RMS roughness of the (11 (2) over bar0) sidewall plane of the pendeo-epitaxial structures of approximately 0.100 nm.