Ohmic contacts to 2D semiconductors through van der Waals bonding

Abstract

High contact resistances have blocked the progress of devices based on MX2 (M = Mo,W; X = S,Se,Te) 2D semiconductors. Interface states formed at MX2/metal contacts pin the Fermi level, leading to sizable Schottky barriers for p-type contacts in particular. We show that (i) one can remove the interface states by covering the metal by a 2D layer, which is van der Waals-bonded to the MX2 layer, and (ii) one can choose the buffer layer such, that it yields a p-type contact with a zero Schottky barrier height. We identify possible buffer layers such as graphene, a monolayer of h-BN, or an oxide layer with a high electron affinity, such as MoO3. The most elegant solution is a metallic M'X'2 layer with a high work function. A NbS2 monolayer adsorbed on a metal yields a high work function contact, irrespective of the metal, which gives a barrierless contact to all MX2 layers.

References in corpus (15)

• Synthesis of Large-Area MoS2 Atomic Layers with Chemical Vapor Deposition
• Doping graphene with metal contacts
• Observation of giant bandgap renormalization and excitonic effects in a monolayer transition metal dichalcogenide semiconductor
• High Performance Single Layered WSe2 p-FETs with Chemically Doped Contacts
• Atomically thin boron nitride: a tunnelling barrier for graphene devices
• Determination of band alignment in the single layer MoS2/WSe2 heterojunction
• Quantitative Determination of the Band-Gap of WS2 with Ambipolar Ionic Liquid-Gated Transistors
• High Mobility WSe2 p- and n-Type Field Effect Transistors Contacted by Highly Doped Graphene for Low-Resistance Contacts
• Electron and Hole Mobilities in Single-Layer WSe2
• High-Performance Monolayer WS2 Field-effect Transistors on High-k Dielectrics
• Controlling the Schottky barrier at MoS2|metal contacts by inserting a BN monolayer
• Low Resistance Metal Contacts to MoS2 Devices with Nickel-Etched-Graphene Electrodes
• Thickness Scaling Effect on Interfacial Barrier and Electrical Contact to Two-Dimensional MoS2 Layers
• Magnetoresistive junctions based on epitaxial graphene and hexagonal boron nitride
• Large potential steps at weakly interacting metal-insulator interfaces

Cited by in corpus (10)

• The role of contact resistance in graphene field-effect devices
• Evidence of Spin Frustration in Vanadium Diselenide Monolayer Magnet
• N- and p-type carrier injections into WSe2 with van der Waals contacts of two-dimensional materials
• Accurate Extraction of Schottky Barrier Height and Universality of Fermi Level De-pinning of van der Waals Contacts
• Degenerately Doped Transition Metal Dichalcogenides as Ohmic Homojunction Contacts to Transition Metal Dichalcogenide Semiconductors
• Direct Opto-Electronic Imaging of 2D Semiconductor - 3D Metal Buried Interfaces
• Bilayer h-BN Barriers for Tunneling Contacts in Fully-Encapsulated Monolayer $\mathbf{MoS}{\mathbf{e}}_2$ Field-Effect Transistors
• Lanthanum Oxyhalide Monolayers: An Exceptional Dielectric Companion to Two-Dimensional Semiconductors
• Excitons in planar quantum wells based on transition metal dichalcogenides
• Step-directed Epitaxy of Uni-directional Hexagonal Boron Nitride on Vicinal Ge(110)