Two-Dimensional Vertical Transistor with One-Dimensional van der Waals Contact.

Abstract

Two-dimensional (2D) materials enable vertical field effect transistors (VFETs), which provide an alternative path for scaling down the channels of transistors. The challenge is the short channel effect when the thickness of the 2D channel decreases to ∼10 nm. Here, we show that a VFET with an ultrashort channel can be accomplished by employing a semimetal carbon nanotube (CNT) as a 1D van der Waals (vdW) contact. The CNT-VFETs with 5-10 nm MoS2 channels exhibit high on/off ratios exceeding 105, low subthreshold swing values of 160-120 mV/dec, and high current densities over 104 A/cm2. Such a switch even works with an ∼ 3.4 nm thick channel. The excellent comprehensive performance can be ascribed to the reduced short channel effect as the sub-2 nm CNT contact has weaker electrostatic screening to the gate, a reduced Fermi level pinning effect, and a highly tunable barrier. The VFETs with 1D vdW contacts hold great promise for ultrascaled transistors and are prospective in future nanoelectronics and nano-optoelectronics.