Interfacial Properties for a Monolayer CrS₂ Contact with Metal: A Theoretical Perspective

Abstract

Limited calculations show that monolayer (ML) chromium dichalcogenide (CrS2) has a direct bandgap and valley polarization but with a smaller bandgap than ML MoS2 and with distinct piezoelectric and ferromagnetic properties. It is highly desirable to determine an appropriate metal contact for novel two‐dimensional (2D) CrS2‐based devices. By using density functional theory (DFT), the interface between ML CrS2 and commonly used metals, including s‐electron and d‐electron metals, is studied systematically by evaluating the binding energy, Schottky barrier, orbital overlap, and tunneling barrier at the interfaces. The d‐electron metals show higher binding energy with the ML CrS2 than the s‐electron metals, which is due to the different occupancy and position of the d‐band of the metals. A strong Fermi level pinning is found in the metal–CrS2 contacts. Both n‐type and quasi p‐type phenomena for CrS2 with respect to pristine CrS2 can be produced at the CrS2 contacts with the metals. The higher overlap states between the CrS2 and Ti result in a higher minimum electron density at the Schottky interface, suggesting that Ti is the best contact among the investigated metals for use in CrS2‐based devices for efficient electron injection. The DFT results provide a guideline that is invaluable for experimentally designing novel 2D CrS2 semiconductor devices.

High‐throughput screening of phase‐engineered atomically thin transition‐metal dichalcogenides for van der Waals contacts at the Schottky–Mott limit

“…Similarly, the S factor of other semiconducting TMDs (e.g., H‐MoS 2 , H‐WSe 2 , P e ‐PdS 2 , H‐MoTe 2 , and T‐PtSe 2 ) with different TMD metals has been calculated. The S values of TMD vdW MSJs located in the range of −0.62 to −0.90 are far larger than those (| S | = 0.001–0.25) of 3D metal‐TMD junctions from previous reports 10,13,25,46–51 . The large S means weak FLP, suggesting the possibility for the realization of depinned contacts in TMD vdW MSJs.…”

“…(B) Interfacial binding energy ( γ int ) versus the Fermi‐level pinning (FLP) factor S in various semiconducting TMDs interacted with different metals. Experimentally measured S values were obtained from 3D metal–TMD junctions based on MoS 2 , 13,25 WSe 2 , 25,46 MoSe 2 , 47 WS 2 , 47 and MoTe 2 , 48 and the calculated S values were obtained from 3D metal‐TMD junctions based on MoS 2 , 49,50 MoSe 2 , 10 MoTe 2 , 10 WS 2 , 10 and CrS 2 51 . (C) Spatial distribution of interfacial local density of states (LDOS) and projected DOS of Au(111)/MoS 2 MSJ.…”

Theoretical Study of Interfacial and Electronic Properties of Transition Metal Dichalcogenides and Organic Molecules Based van der Waals Heterostructures

“…We calculated the plane average charge density difference in TMD/organic heterostructure using Equation (3). The change in diople moment due to rearrangement of charge can be computed using the following equation [ 40,46 ] , where z axis is perpendicular to the MX 2 monolayer and L is the length of MX 2 /organic system along z direction. The change in dipole moment due to the charge transfer and charge rearrangement in MX 2 /organic heterostructures are tabulated in the Table S1 (Supporting Information), which explains the change in work function of monolayer MX 2 after introducing organic layer.…”

Device Simulation of 5.1 nm High-Performance Field-Effect Transistors Based on Two-Dimensional Boron Phosphide

“…A small impediment of charge injection requires low ϕ TB and narrow W TB , so as to be beneficial for device performance. In this work, the ϕ TB is defined as the difference between the Fermi level of the 2D metal/BP heterostructure and the peak potential of the metal/BP contact gap (ϕ gap ), and the W TB is defined as the full width at half maximum of the ϕ TB . , In the case of the BoroΔ/BP heterostructure, the Fermi level is located above the peak potential of the gap. Thus, there is no barrier at the interface of two monolayers, indicating a large charge injection in the BP FET with the BoroΔ source.…”