Performance of the Pentagonal PdSe₂ Sheet as a Channel Material in Contact with Metal Surfaces and Graphene

Abstract

Motivated by the recent synthesis of the pentagonal PdSe 2 sheet [J. Am. Chem. Soc. 2017, 139, 14090], here using first-principles calculations, we have systematically carried out simulations to investigate the PdSe 2 sheet's performance as a channel material when in contact with metal surfaces and graphene. We find that the PdSe 2 sheet can almost retain its pentagonal feature with small distortions when in contact with Au(111), Ag(111), Cu(111), and Pb(111) surfaces. However, it is severely distorted on the Ti(0001) surface undergoing metallization. Band structure analysis suggests that the vertical Schottky barrier disappears in all of the metal contacts. Au, Ag, Cu, Ti, and Pb are of the Schottky type contacts with barriers of 0.62, 0.87, 0.79, 0.58, and 0.76 eV in the lateral direction for electrons, whereas both monolayer and bilayer PdSe 2 maintain their intrinsic properties when in contact with graphene forming a weak van der Waals interaction with no charge transfer between the two surfaces. Our study provides insights into selecting high-performance monolayer PdSe 2 device evaluations based on the orbital overlap, tunneling barrier, and Schottky barrier.

First-Principles Study of the Structural, Electronic, and Enhanced Optical Properties of SnS/TaS2 Heterojunction

“…The atomic positions are fully relaxed with an energy convergence criterion of 10 −5 eV and force convergence of 0.01 eV/Å. 39 In addition, the thermal stability of the proposed structures is studied using ab initio molecular dynamics (AIMD) simulations, where the canonical ensemble (NVT) is employed and temperature control is achieved with the Noséthermostat. 40 All optical properties can be deduced from the complex dielectric function ε(ω) = ε 1 (ω) + iε 2 (ω).…”

“…Motivated by the preparation of the SnS/TaS 2 superlattice, 28 here we construct the SnS/TaS 2 heterojunction by vertically stacking the two monolayers together (see Figure 2). Due to the different lattice symmetries, the lattice match is carefully handled using our in-house code, 39 where the mismatch is set to be less than 3% to reduce the internal strain. For saving the computing cost, we have built several stacking structures with the minimum number of atoms.…”

Applications of 2D-Layered Palladium Diselenide and Its van der Waals Heterostructures in Electronics and Optoelectronics

“…Theoretical calculations using the DFT approach were employed to compare the metal/PdSe 2 contact performances by tuning the metal types such as Au, Ag, Pb, Cu, and Ti, as well as semimetallic graphene. The efficiency of charge transfer at the PdSe 2 –metal interface was examined for energy barrier evaluation [ 69 ]. Figure 16 a shows the prototype of a PdSe 2 –metal contact with a carrier flowing from the metal electrode to the PdSe 2 channel through the pathway (I → II → III → IV → V).…”

“…Eventually, the graphene/PdSe 2 contact has emerged as a proof of concept with regard to vdWHs. A Schottky barrier height of 0.22 eV is preferred for electron transport—that is, n -type charge carrier conductance [ 69 ]. Indeed, electrons are transferred from the interface to the PdSe 2 side with a band bending of − 0.94.…”

Site-specific symmetry sensitivity of angle-resolved photoemission spectroscopy in layered palladium diselenide

“…In addition, a linear dependence of the band gap with the number of layers has been observed [3,16]: the monolayer is predicted to have an indirect gap of 1.3 eV [17] which monotonically decreases to 0 eV as the thickness exceeds 40 − 50 layers, suggesting semimetallic behavior. However, unlike black phosphorous and the majority of TMDs which share hexagonal crystal structures, the low-symmetry pentagonal atomic arrangement of PdSe 2 gives rise to exotic thermoelectric, mechanical and optical properties [18][19][20].…”