Interfacial Properties of Monolayer MoSe₂–Metal Contacts

Abstract

Monolayer (ML) transition-metal dichalcogenides are considered as promising channel materials in next-generation transistors. Using ab initio energy band calculations and more reliable ab initio quantum transport simulations, we study the interfacial properties of ML MoSe 2 −metal interfaces (metals = Al, Ag, Pt, Cr, Ni, and Ti). Weak or medium adsorption is found between ML MoSe 2 and the Al, Ag, and Pt surfaces with the band structure of ML MoSe 2 preserved, while strong adsorption is found between ML MoSe 2 and the Ni, Ti, and Cr surfaces with the band structure of ML MoSe 2 destroyed. The two methods give similar polarity and height of Schottky barriers for ML MoSe 2 with Al, Ag, Pt, and Ti electrodes. ML MoSe 2 forms an n-type Schottky contact with Ag, Ti, and Al electrodes with electron Schottky barrier heights (SBH) of 0.25, 0.29, and 0.56 eV, respectively, and a p-type Schottky contact with Pt electrode with hole SBH of 0.78 eV according to ab initio quantum transport simulations. Our study offers a guidance for the choices of suitable metal electrodes in ML MoSe 2 devices.

A computational study of monolayer hexagonal WTe2 to metal interfaces

“…Our previous study shows that for a weakly absorbed system with an identifiable semiconductor band structure, the vertical SBH obtained by the band calculation in a semi‐infinite interfacial model is approximately consistent with the one obtained by the quantum transport simulation in a FET model. The reason lies in the interaction between the metal and ML 2H WTe 2 has been taken into consideration for both models.…”

“…A lot of studies for the interfacial properties between various metal electrodes (Sc, Ti, Al, Ag, Cu, Au, Ni, Pd, Pt, and Cr) and 2H MoS 2 , MoSe 2 , and WSe 2 have been performed [31][32][33][34][35][36][37][38][39]. However, a systemic study for the interfacial properties of metal-ML 2H WTe 2 has not been introduced until now, to the best of our knowledge.…”

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

“…The calculated partial density of states (PDOS) and band structure for ML CrS 2 (Figure (b)) show that ML CrS 2 is a direct bandgap semiconductor with a gap of 0.951 eV, which is consistent with the value of 1.07 eV obtained from previous DFT calculations . The metals are found to be either weakly or strongly adsorbed onto the CrS 2 surface, depending on the nature of the metal d orbitals, similar to other TMDs . The unique interaction strength between the metal and ML CrS 2 is well characterized by the different binding energies ( E b ) and the equilibrium interfacial separation ( d S‐M ).…”

“…Due to deficiency in orbital overlap, Ag‐ or Au‐CrS 2 exhibits a distinctive n‐type Schottky contact (Figure a and b). The open d ‐shell of d ‐electron metals is more favorable to overlap with the d orbitals of CrS 2 compared to the full d ‐shell of s ‐electron metals as has also been found in other TMDs …”

“…[6] The metals are found to be either weakly or strongly adsorbed onto the CrS 2 surface, depending on the nature of the metal d orbitals, similar to other TMDs. [24][25][26][27] The unique interaction strength between the metal and ML CrS 2 is well characterized by the different binding energies (E b ) and the equilibrium interfacial separation (d S-M ). The d S-M (denoted in Figure 2(a)), defined as the vertical distance between the bottom metal layer and the topmost S atoms of CrS 2 , ranges from 1.60 to 2.52 Åand increases in the order of Sc < Ti < Pt < Pd < Ag < Au.…”