Contact-Induced Semiconductor-to-Metal Transition in Single-Layer WS${}_2$

Abstract

Low-resistance ohmic contacts are a challenge for electronic devices based on two-dimensional materials. We show that an atomically precise junction between a two-dimensional semiconductor and a metallic contact can lead to a semiconductor-to-metal transition in the two-dimensional material--a finding which points the way to a possible method of achieving low-resistance junctions. Specifically, single-layer WS${}_2$ undergoes a semiconductor-to-metal transition when epitaxially grown on Ag(111), while it remains a direct band gap semiconductor on Au(111). The metallicity of the single layer on Ag(111) is established by lineshape analysis of core level photoemission spectra. Angle-resolved photoemission spectroscopy locates the metallic states near the Q point of the WS${}_2$ Brillouin zone. Density functional theory calculations show that the metallic states arise from hybridization between Ag bulk bands and the local conduction band minimum of WS${}_2$ near the Q point.

Main text: 21 pages, 4 figures. Supplement: 7 pages, 4 figures, 1 table

References in corpus (7)

• Observation of giant bandgap renormalization and excitonic effects in a monolayer transition metal dichalcogenide semiconductor
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Cited by in corpus (1)

• Epitaxial single layer NbS${}_2$ on Au(111): synthesis, structure, and electronic properties