An integrated circuit device is disclosed. An exemplary integrated circuit device includes: a semiconductor substrate; a fin structure disposed over the semiconductor substrate; and a gate structure disposed over the base portion of the fin structure. The collector portion is a first doped region including a first type dopant, and is coupled with a first terminal for electrically biasing the collector portion. The emitter portion is a second doped region including the first type dopant, and is coupled with a second terminal for electrically biasing the emitter portion. The base portion is a third doped region including a second type dopant opposite the first type, and is coupled with a third terminal for electrically biasing the base portion. The gate structure is coupled with a fourth terminal for electrically biasing the gate structure, such that the gate structure controls a path of current through the base portion.