III-N devices in Si trenches

An electronic device, comprising

• a plurality of trenches in a trench layer on a planar surface of a substrate, the plurality of trenches exposing portions of the planar surface of the substrate, wherein the trench layer is an insulating layer or a metallic layer, and wherein the substrate is a semiconductor substrate;
• a nucleation layer on the exposed portions of the planar surface of the substrate within the trenches, wherein a bottommost surface of the nucleation layer is co-planar with a bottommost surface of the trench layer;
• and
• a III-N material layer on the nucleation layer, wherein the III-N material layer extends laterally over the trenches.