One-dimensional semimetal contacts to two-dimensional semiconductors.

Two-dimensional (2D) semiconductors are promising in channel length scaling of field-effect transistors (FETs) due to their excellent gate electrostatics. However, scaling of their contact length still remains a significant challenge because of the sharply raised contact resistance and the deteriorated metal conductivity at nanoscale. Here, we construct a 1D semimetal-2D semiconductor contact by employing single-walled carbon nanotube electrodes, which can push the contact length into the sub-2 nm region. Such 1D–2D heterostructures exhibit smaller van der Waals gaps than the 2D–2D ones, while the Schottky barrier height can be effectively tuned via gate potential to achieve Ohmic contact. We propose a longitudinal transmission line model for analyzing the potential and current distribution of devices in short contact limit, and use it to extract the 1D–2D contact resistivity which is as low as 10⁻⁶ Ω·cm² for the ultra-short contacts. We further demonstrate that the semimetal nanotubes with gate-tunable work function could form good contacts to various 2D semiconductors including MoS₂, WS₂ and WSe₂. The study on 1D semimetal contact provides a basis for further miniaturization of nanoelectronics in the future. 2D semiconductors are attracting increasing attention as potentially scalable channels for future transistors, but the scaling of their contact length remains challenging. Here, the authors report the realization of 1D semimetal-2D semiconductor contacts based on individual carbon nanotubes with contact length down to 2 nm. [ABSTRACT FROM AUTHOR]