Abstract: In a method for making a GaN article, an epitaxial nitride layer is deposited on a single-crystal substrate. A 3D nucleation GaN layer is grown on the epitaxial nitride layer by HVPE under a substantially 3D growth mode. A GaN transitional layer is grown on the 3D nucleation layer by HVPE under a condition that changes the growth mode from the substantially 3D growth mode to a substantially 2D growth mode. A bulk GaN layer is grown on the transitional layer by HVPE under the substantially 2D growth mode. A polycrystalline GaN layer is grown on the bulk GaN layer to form a GaN/substrate bi-layer. The GaN/substrate bi-layer may be cooled from the growth temperature to an ambient temperature, wherein GaN material cracks laterally and separates from the substrate, forming a free-standing article.

Abstract: A templated substate includes a base layer, and a template layer disposed on the base layer and having a composition including a single-crystal Group Ill nitride. The template layer includes a continuous sublayer on the base layer and a nanocolumnar sublayer on the first sublayer, wherein the nanocolumnar sublayer includes a plurality of nano-scale columns.