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.

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

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• In-situ exfoliation method of large-area 2D materials
• Spin structure of K valleys in single-layer WS${}_2$ on Au(111)
• Tunneling-current-induced local excitonic luminescence in p-doped WSe${}_2$ monolayers
• Nanoscale patterning of quasiparticle band alignment
• Epitaxial single layer NbS${}_2$ on Au(111): synthesis, structure, and electronic properties
• Correlation-induced magnetism in substrate-supported 2D metal-organic frameworks
• Charge transfer-induced Lifshitz transition and magnetic symmetry breaking in ultrathin CrSBr crystals
• Monolayers of MoS${}_2$ on Ag(111) as decoupling layers for organic molecules: resolution of electronic and vibronic states of TCNQ
• Momentum-resolved linear dichroism in bilayer MoS${}_2$
• Quasi-free-standing single-layer WS2 achieved by intercalation
• Moiré induced electronic structure modifications in monolayer V${}_2$S${}_3$ on Au(111)
• An autoencoder for compressing angle-resolved photoemission spectroscopy data