Electronic Transport along Hybrid MoS 2 Monolayers Ganesh Sivaraman, †,∥ Fa ́ bio A. L. de Souza, ‡,∥ Rodrigo G. Amorim, §,¶ Wanderla ̃ L. Scopel, ‡ Maria Fyta,* ,† and Ralph H. Scheicher* ,§ † Institute for Computational Physics, Universitä t Stuttgart, Allmandring 3, 70569 Stuttgart, Germany ‡ Departamento de Física, Universidade Federal do Espírito Santo-UFES, Vitó ria, Espírito Santo, Brazil § Department of Physics and Astronomy, Materials Theory, Uppsala University, Box 516, SE-751 20 Uppsala, Sweden ¶ Departamento de Física, ICEx, Universidade Federal Fluminense - UFF, Volta Redonda, Rio de Janeiro, Brazil ABSTRACT: Molybdenum disulfide (MoS 2 ) is a two-dimensional material in which a semiconducting and a metallic phase can coexist. In this work, we investigate the electronic and transport properties of a hybrid MoS 2 monolayer composed of a metallic strip embedded in the semiconducting MoS 2 phase. Using quantum mechanical calculations within the density functional theory scheme together with the non-equilibrium Greens functions approach, we study in detail the structural and electronic properties of this hybrid material and its metal− semiconductor interface. A single point-defect analysis is performed in order to assess the stability of the hybrid system. Focus is given to the electronic transport properties of the hybrid MoS 2 monolayer extracted from the electronic transmission spectra. These are linked to the local current across the monolayer. A clear asymmetry of the current flowing across the hybrid monolayer was found and was attributed to the atomistic characteristics of the material’s interfaces. The results suggest strong potential for the application of hybrid MoS 2 in the next generation biosensing devices. ■ INTRODUCTION Two-dimensional (2D) materials have attracted high interest in recent years. Starting with graphene and its numerous potential applications, the research of 2D nanomaterials 1,2 was followed by intense investigations on 2D transition metal dichalcoge- nides (TMDs). 3,4 TMDs (MX 2 , with M = V, Mo, W, etc., and X = S, Se, etc.) are quasi two-dimensional layered materials with strong interlayer ionic−covalent bonding. 2D TMDs can be found in two phases, semiconducting (2H) and metallic (1T). Liquid-phase exfoliation is the typical method to produce the monolayer TMDs from their layered counterparts. 5,6 It was shown that the transition from the 2H to the 1T phase of MoS 2 , MoSe 2 , WS 2 , and WSe 2 during their chemical exfoliation depends on the MX 2 composition of these materials. 7 The most famous member of the 2D TMD family is MoS 2 , which has been used as a dry lubricant for many decades in its bulk form. In the earlier studies, focus was given on MoS 2 -based nanoparticles, such as MoS 2 nested inorganic fullerenes, nanotubes, 8 and MoS 2 nanoclusters 9 used as catalysts. 10 The investigations then turned to MoS 2 surfaces 11,12 and their ability to adsorb hydrogen. 13 The research on MoS 2 has shown a 4-fold increase since the year 2010 when the direct band gap in the single-layered structure was discovered. 4, 14 The coexistence of a metallic and semiconducting phase has been reported in MoS 2 in the past in several studies. 15−17 This represents a distinct polymorphism in terms of structural and electronic properties, a marked deviation from graphene. The coexistence of the semiconducting (2H) and metallic (1T) phase in MoS 2 monolayers has been characterized. 18−21 In principle, gliding only one S plane of MoS 2 to the center of the hexagonal rings of the semiconducting 2H phase will gradually transform the structure to the metallic 1T phase. 15 During this transformation, while the size of the 1T part increases, three different boundariesα, β, and γemerge. The α boundary is related to the Mo−Mo distance shrinking, the β boundary involves the Mo + S gliding, and the γ boundary is based on the S gliding. 15 The recent development of controlled techniques to induce 2H to 1T phase transition 15,22 opens up promising routes for an atomically precise fabrication of single-layered chemically homogeneous electronic devices. Lately, another important achievement in the field was the formation of nanopores in MoS 2 . 23 These nanopores are formed using an electrochemical reaction method, 24 and it has been demon- strated that DNA can be translocated through them within a salt solution. 25 These nanopores are efficient in discriminating among DNA nucleotides 26 and can lead to a novel sequencing technique. 27,28 In this study, we focus on hybrid monolayers of MoS 2 . The term “hybrid” refers to the combination of the two different phases (2H and 1T) composing the monolayer. It accounts for the polymorphicity of MoS 2 linking to materials with tunable functionalities. The combination of different phases in Received: August 5, 2016 Revised: September 19, 2016 Article pubs.acs.org/JPCC © XXXX American Chemical Society A DOI: 10.1021/acs.jpcc.6b07917 J. Phys. Chem. C XXXX, XXX, XXX−XXX