Abstract: A method of maskless lateral epitaxial overgrowth (LEO) of aluminum nitride (AlN) and high aluminum composition aluminum gallium nitride (AlGaN) layers by crystal growth techniques, such as metalorganic chemical vapor deposition (MOCVD), Hydride Vapor Phase Epitaxy (HVPE), other vapor phase transport techniques such as sublimation, and Molecular Beam Epitaxy (MBE). The process etches periodic patterns into a suitable material, such AlN or high aluminum composition AlGaN base layers heteroepitaxially grown on a substrate or a substrate itself. A lateral epitaxial overgrowth is performed of the AlN or high aluminum composition AlGaN layers on the suitable material. Lateral epitaxial overgrowth of the AlN or high aluminum composition AlGaN layers may be enhanced by using low V/III ratios and fast growth rates. The process reduces the threading dislocation density (TDD) in high Al containing nitrides by several orders of magnitude.