Theoretical Analysis of a 2D Metallic/Semiconducting Transition‐Metal Dichalcogenide NbS₂//WSe₂ Hybrid Interface

Abstract

A first-principles theoretical study of a monolayer-thick lateral heterostructure (LH) joining two different transition metal dichalcogenides, NbS 2 and WSe 2 , is reported. The NbS 2 //WSe 2 LH can be considered a prototypical example of a metal (NbS 2)/semiconductor (WSe 2) 2D hybrid heterojunction. First, realistic atomistic models of the NbS 2 //WSe 2 LH are generated and validated, its band structure is derived, and it is subjected to a fragment decomposition and electrostatic potential analysis to extract a simple but quantitative model of this interfacial system. Stoichiometric fluctuations models are also investigated and found not to alter the qualitative picture. Then, electron transport simulations are conducted and they are analyzed via band alignment analysis. It is concluded that the NbS 2 //WSe 2 LH appears as a robust seamless in-plane 2D modular junction for potential use in optoelectronic devices going beyond the present miniaturization technology.

Vertical Heterostructures between Transition‐Metal Dichalcogenides—A Theoretical Analysis of the NbS2/WSe2 Junction

“…We performed DFT and transport simulations on the configurations built in Section 2, and complemented them with an analysis [21] based on partitioning a composite system and understanding its behavior in terms of constituent fragments, using the electrostatic potential as a unifying descriptor. Comparison with a previous study on the LH of the same NbS2/WSe2 materials combination [20] will allow us to assess the relative merits of the two interfaces.…”

“…We then introduce a simple model combining atomic PDOS and hopping elements at the interface as derived from a Wannier analysis of the wave function, and show that this model can now accurately explain the computational results, in particular the presence or absence of a double-peak profile in transmission depending on interfacial distances. Also, in comparison with the homologous WSe2/NbS2 lateral heterostructure [20], the wide-interval and double-peak-profile transmission here found for the VH system is of interest for potential applications, while the theoretical fragment, alignment, and Wannier analysis of electronic transmission should be generally applicable to the study of transport in 2D materials.…”

“…[ 21] and applied to the NbS2/WSe2 LH in Ref. [ 20], so that the final plot corresponds to the local Fermi energy (loc-EF) for the NbS2 metallic fragment and the local top of the valence band (loc-TVB) for the WSe2 semiconductor fragment. In practice, we build up a fragment 2H bulk NbS2 phase by replicating the geometry in the middle of the NbS2 phase, we extract from this calculation the difference between the Fermi energy (EF) of the system and the electrostatic potential on the Nb atom, and we report this difference onto the NbS2/WSe2 VH by adding it to the values of the electrostatic potential on Nb atoms in the scattering region, thus finally determining the local Fermi energy EF (loc-EF).…”

“…They also showed that the presence of localized states due to the interface or to doping can modulate the barrier height. In previous work, we estimated the SBH from the jump in electrostatic potential at the interface [20], i.e., by the difference between the local Fermi energy of the metallic part and the local TBV of the semiconductor part precisely at the interface, where a fragmentanalysis method was used to obtain the needed alignment of the two components [21]. The origin and nature of Schottky barriers in TMD monolayers (MX2 where M = Mo, W and X = S, Se, Te) in contact with an ideal metal electrode have been studied by D. Szczęśniak et al [22] using combination of the complex band structure formalism and the cell-averaged Green's function technique.…”

Rational Design of Tungsten Selenide @ N‐Doped Carbon Nanotube for High‐Stable Potassium‐Ion Batteries

“…As shown in Figure 4c, the pristine WSe 2 shows its semiconducting nature. [ 40 ] After adsorption of K on the WSe 2 monolayer, the Fermi level migrated to the conduction band, indicating the introduction of K will effectively promote the electronic conductivity of WSe 2 . (Figure 4d, Figure S8, Supporting Information).…”