An Ultralow Power Mixed Dimensional Heterojunction Transistor Based on the Charge Plasma pn Junction

Abstract Development of a reliable doping method for 2D materials is a key issue to adopt the materials in the future microelectronic circuits and to replace the silicon, keeping the Moore's law toward the sub‐10 nm channel length. Especially hole doping is highly required, because most of the transition metal dichalcogenides (TMDC) among the 2D materials are electron‐doped by sulfur vacancies in their atomic structures. Here, hole doping of a TMDC, tungsten disulfide (WS₂) using the silicon substrate as the dopant medium is demonstrated. An ultralow‐power current sourcing transistor or a gated WS₂ pn diode is fabricated based on a charge plasma pn heterojunction formed between the WS₂ thin‐film and heavily doped bulk silicon. An ultralow switchable output current down to 0.01 nA µm⁻¹, an off‐state current of ≈1 × 10⁻¹⁴ A µm⁻¹, a static power consumption range of 1 fW µm⁻¹–1 pW µm⁻¹, and an output current ratio of 10³ at 0.1 V supply voltage are achieved. The charge plasma heterojunction allows a stable (less than 3% variation) output current regardless of the gate voltage once it is turned on.