Bilayer tungsten diselenide transistors with on-state currents exceeding 1.5 milliamperes per micrometre

Two-dimensional semiconductors such as layered transition metal dichalcogenides can offer superior immunity to short-channel effects compared with bulk semiconductors such as silicon. As a result, these materials can be used to create highly scaled transistors. However, on-state current densities of two-dimensional semiconductor transistors are still below those of silicon transistors. Here we show that bilayer tungsten diselenide transistors that have channel lengths of less than 100 nm can exhibit on-state current densities above 1.0 mA μm−1 and on-state resistances below 1.0 kΩ μm at room temperature. The devices have atomically clean van der Waals vanadium diselenide contacts and are created using van der Waals epitaxy and controlled crack formation processes. With a 20-nm-long and 1.3-nm-thick transistor, an on-state current density of 1.72 mA μm−1 and on-state resistance of 0.50 kΩ μm are achieved, showing comparable performance to silicon transistors with similar channel lengths and driving voltages.