Two-dimensional (2D) semiconductors are promising for low-power complementary metal oxide semiconductor (CMOS) electronics, which require ultrathin n- and p-type transistor channels. Among 2D semiconductors, WS2 is expected to have good conduction for both electrons and holes, but p-type WS2 transistors have been difficult to realize due to the relatively deep valence band and the presence of mid-gap states with conventional metal contacts. Here, we report topological semimetal NbP as p-type electrical contacts to bilayer WS2 with up to 5.8 microamperes per micron hole current at room temperature; this is the highest to date for sub 2 nm thin WS2 and more than 50 times larger than with metals like Ni or Pd. The p-type conduction is enabled by the simultaneously high work function and low density of states of the NbP, which reduce Fermi level pinning. These contacts are sputter-deposited at room temperature, an approach compatible with CMOS fabrication, a step towards enabling ultrathin WS2 semiconductors in future nanoelectronics.
@article{arxiv.2409.18926,
title = {Enabling P-type Conduction in Bilayer WS2 with NbP Topological Semimetal Contacts},
author = {Lauren Hoang and Asir Intisar Khan and Robert K. A. Bennett and Hyun-mi Kim and Zhepeng Zhang and Marisa Hocking and Ae Rim Choi and Il-Kwon Oh and Andrew J. Mannix and Eric Pop},
journal= {arXiv preprint arXiv:2409.18926},
year = {2024}
}