Embodiments herein describe techniques for a semiconductor device, which may include a substrate, a metallic encapsulation layer above the substrate, and a gate electrode above the substrate and next to the metallic encapsulation layer. A channel layer may be above the metallic encapsulation layer and the gate electrode, where the channel layer may include a source area and a drain area. In addition, a source electrode may be coupled to the source area, and a drain electrode may be coupled to the drain area. Other embodiments may be described and/or claimed.