title: Van der Waals metal-semiconductor junction: Weak Fermi level pinning enables effective tuning of Schottky barrier.
abstract: Two-dimensional (2D) semiconductors have shown great potential for electronic and optoelectronic applications. However, their development is limited by a large Schottky barrier (SB) at the metal-semiconductor junction (MSJ), which is difficult to tune by using conventional metals because of the effect of strong Fermi level pinning (FLP). We show that this problem can be overcome by using 2D metals, which are bounded with 2D semiconductors through van der Waals (vdW) interactions. This success relies on a weak FLP at the vdW MSJ, which is attributed to the suppression of metal-induced gap states. Consequently, the SB becomes tunable and can vanish with proper 2D metals (for example, H-NbS2). This work not only offers new insights into the fundamental properties of heterojunctions but also uncovers the great potential of 2D metals for device applications.
authors.affiliation: National Renewable Energy Laboratory, Golden, CO 80401, USA.
authors.forename: Yuanyue
authors.initials: Y
authors.lastname: Liu
authors.affiliation: National Renewable Energy Laboratory, Golden, CO 80401, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Stradins
authors.affiliation: National Renewable Energy Laboratory, Golden, CO 80401, USA.; Beijing Computational Science Research Center, Beijing 100094, China.
authors.forename: Su-Huai
authors.initials: SH
authors.lastname: Wei
mesh_terms: D008670:Metals / Q000737:chemistry*; D055095:Optics and Photonics / Q000295:instrumentation*; D012666:Semiconductors
chemical_list: D008670:Metals
keywords: Two-dimensional materials; heterojunctions