Two-Dimensional\nVertical Transistor with One-Dimensional\nvan der Waals Contact

Two-dimensional (2D) materials enable vertical field\neffect transistors\n(VFETs), which provide an alternative path for scaling down the channels\nof transistors. The challenge is the short channel effect when the\nthickness of the 2D channel decreases to ∼10 nm. Here, we show\nthat a VFET with an ultrashort channel can be accomplished by employing\na semimetal carbon nanotube (CNT) as a 1D van der Waals (vdW) contact.\nThe CNT-VFETs with 5–10 nm MoS<sub>2</sub> channels exhibit\nhigh on/off ratios exceeding 10<sup>5</sup>, low subthreshold swing\nvalues of 160–120 mV/dec, and high current densities over 10<sup>4</sup> A/cm<sup>2</sup>. Such a switch even works with an ∼\n3.4 nm thick channel. The excellent comprehensive performance can\nbe ascribed to the reduced short channel effect as the sub-2 nm CNT\ncontact has weaker electrostatic screening to the gate, a reduced\nFermi level pinning effect, and a highly tunable barrier. The VFETs\nwith 1D vdW contacts hold great promise for ultrascaled transistors\nand are prospective in future nanoelectronics and nano-optoelectronics.