The current disclosure describes semiconductor devices, e.g., transistors including a thin semimetal layer as a channel region over a substrate, which includes bandgap opening and exhibits semiconductor properties. Described semiconductor devices include source/drain regions that include a thicker semimetal layer over the thin semimetal layer serving as the channel region, this thicker semimetal layer exhibiting metal properties. The semimetal used for the source/drain regions include a same or similar semimetal material as the semimetal of the channel region.