Comprehensive tunneling spectroscopy of quasi-freestanding MoS${}_2$ on graphene on Ir(111)

Abstract

We apply scanning tunneling spectroscopy to determine the bandgaps of mono-, bi- and trilayer MoS${}_2$ grown on a graphene single crystal on Ir(111). Besides the typical scanning tunneling spectroscopy at constant height, we employ two additional spectroscopic methods giving extra sensitivity and qualitative insight into the $k$-vector of the tunneling electrons. Employing this comprehensive set of spectroscopic methods in tandem, we deduce a bandgap of $2.53\pm 0.08$ eV for the monolayer. This is close to the predicted values for freestanding MoS${}_2$ and larger than is measured for MoS${}_2$ on other substrates. Through precise analysis of the `comprehensive' tunneling spectroscopy we also identify critical point energies in the mono- and bilayer MoS${}_2$ band structures. These compare well with their calculated freestanding equivalents, evidencing the graphene/Ir(111) substrate as an excellent environment upon which to study the many feted electronic phenomena of monolayer MoS${}_2$ and similar materials. Additionally, this investigation serves to expand the fledgling field of the comprehensive tunneling spectroscopy technique itself.

8 pages, 5 figures, accepted

References in corpus (4)

• Two Dimensional Atomic Crystals
• Quasiparticle band structures and optical properties of strained monolayer MoS2 and WS2
• Electronic Structure of Epitaxial Single-Layer MoS${}_2$
• Carrier Plasmon Induced Nonlinear Band Gap Renormalization in Two-Dimensional Semiconductors

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• Metal-insulator transition in monolayer MoS${}_2$ via contactless chemical doping
• Single-crystal graphene on Ir(110)
• Tip-induced creation and Jahn-Teller distortions of sulfur vacancies in single-layer MoS${}_2$
• Moiré induced electronic structure modifications in monolayer V${}_2$S${}_3$ on Au(111)
• Visualizing intercalation effects in 2D materials using AFM based techniques