A device includes a layer including a first III-Nitride (III-N) material, a channel layer including a second III-N material, a release layer including nitrogen and a transition metal, where the release layer is between the first III-N material and the second III-N material. The device further includes a polarization layer including a third III-N material above the release layer, a gate structure above the polarization layer, a source structure and a drain structure on opposite sides of the gate structure where the source structure and the drain structure each include a fourth III-N material. The device further includes a source contact on the source structure and a drain contact on the drain structure.