Scanning tunneling spectroscopy of van der Waals graphene/semiconductor interfaces: absence of Fermi level pinning. (24th July 2017)

• Record Type: Journal Article
• Authors: Le Quang, T; Cherkez, V; Nogajewski, K; Potemski, M; Dau, M T; Jamet, M; Mallet, P; Veuillen, J-Y
• Is Part Of: 2D materials. Volume 4:Number 3(2017)
• Publication Date: 2017-07-24
• Subjects: scanning tunneling microscopy/spectroscopy -- Van der Waals heterostructures -- Schottky-Mott model -- Schottky barrier height -- graphene -- TMD; Graphene -- Periodicals; Materials science -- Periodicals; Nanostructured materials -- Periodicals; 620.115
• DOI: 10.1088/2053-1583/aa7b03
• Languages: English
• ISSNs: 2053-1583

Abstract

Abstract: We have investigated the electronic properties of two-dimensional (2D) transition metal dichalcogenides (TMDs), namely trilayer WSe2 and monolayer MoSe2, deposited on epitaxial graphene on silicon carbide, by using scanning tunneling microscopy and spectroscopy (STM/STS) in ultra-high vacuum. Depending on the number of graphene layers below the TMD flakes, we identified variations in the electronic d I /d V (V) spectra measured by the STM tip: the most salient feature is a rigid shift of the TMD spectra (i.e. of the different band onset positions) towards occupied states by about 120 mV when passing from bilayer to monolayer underlying graphene. Since both graphene phases are metallic and present a work function difference in the same energy range, our measurements point towards the absence of Fermi-level pinning for such van der Waals 2D TMD/Metal heterojunctions, following the prediction of the Schottky-Mott model.