Highly Controllable Polarity in Two-Dimensional Vertical Transistors

Abstract

Two-dimensional (2D) vertical transistors, featuring atomically thin channels and an inherent vertical architecture, hold extensive promise for ultrascaled electronics. However, achieving reliable polarity control in such devices has remained a persistent challenge over the past decade. Here, we demonstrate a vertical MoTe₂ transistor with highly controllable polarity. By implementing van der Waals (vdW) integration for both contacts, the carrier injection barrier can be effectively modulated via the work functions of the electrodes. Leveraging the favorable band alignment with graphene and the narrow bandgap of MoTe₂, we achieve selective n-type and p-type operation using Ag and Pt top contacts, respectively. Furthermore, through graphene work-function engineering, we optimize the switching performance, realizing an on/off ratio exceeding 10⁴ in a ∼5 nm p-type MoTe₂ vertical transistor, surpassing all previously reported p-type 2D vertical transistors based on graphene/TMD/metal architectures. Finally, we integrate two vertical transistors of opposite polarities, fabricated from graphene/MoTe₂ heterostructure with different top contacts, to demonstrate a complementary inverter on a single chip. Our work not only provides a viable strategy for polarity control in vertical heterostructures but also suggests a potential pathway toward complementary circuits based on 2D vertical transistors.