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

Abstract

Low-dimensional metal-semiconductor vertical heterostructures (VH) are promising candidates in the search of electronic devices at the extreme limits of miniaturization. Within this line of research, here we present a theoretical/computational study of the NbS2/WSe2 metalsemiconductor vertical hetero-junction using density functional theory (DFT) and conductance simulations. We first construct atomistic models of the NbS2/WSe2 VH considering all the five possible stacking orientations at the interface, and we conduct DFT and quantum-mechanical (QM) scattering simulations to obtain information on band structure and transmission coefficients. We then carry out an analysis of the QM results in terms of electrostatic potential, fragment decomposition, and band alignment. The behavior of transmission expected from this analysis is in excellent agreement with, and thus fully rationalizes, the DFT results, and the peculiar doublepeak profile of transmission. Finally, we use maximally localized Wannier functions, projected density of states (PDOS), and a simple analytic formula to predict and explain quantitatively the differences in transport in the case of epitaxial misorientation. Within the class of Transition-Metal Dichalcogenide systems, the NbS2/WSe2 vertical heterostructure exhibits a wide interval of finite transmission and a double-peak profile, features that could be exploited in applications.

Electrostatic tuning of transmission in NbS2/WSe2 Lateral Hetero-Structures: A computational study

“…Previously, we derived quantitative modeling of electron transport in the NbS 2 /WSe 2 metal/semiconductor junction, and found it to be a promising system for potential applications, since e.g. stoichiometric fluctuations stabilize the system without deteriorating its electronic features [40][41]. To perturb the conductance of this system within an electrostatic scenario, we introduce point defects, with the goal of modelling charged or dipolar defects in the substrate.…”

“…We found it to be a promising system for potential applications, such as FET, since e.g. stoichiometric fluctuations stabilize the system without deteriorating its electronic features [40][41]. For these reasons, we consider NbS 2 /WSe 2 as an ideal system to investigate defect modelling.…”

Electrostatic tuning of transmission in NbS2/WSe2 Lateral Hetero-Structures: A computational study

“…Previously, we derived quantitative modeling of electron transport in the NbS 2 /WSe 2 metal/semiconductor junction, and found it to be a promising system for potential applications, since e.g. stoichiometric fluctuations stabilize the system without deteriorating its electronic features [39][40]. To perturb the conductance of this system within an electrostatic scenario, we introduce electrostatic defects, with the goal of modelling charged or dipolar defects in the substrate.…”

“…We found it to be a promising system for potential applications, such as FET, since e.g. stoichiometric fluctuations stabilize the system without deteriorating its electronic features [39][40]. For these reasons, we consider NbS 2 /WSe 2 as an ideal system to investigate defect modelling.…”

Ideal Vacuum-Based Efficient and High-Throughput Computational Screening of Type II Heterojunctions

“…The most straightforward way to predict the band alignment in a heterojunction is explicitly building an interface model with sufficient layers of atoms, such as the alternating slab junction or surface-terminated junction. − The advantage of such a protocol is that the effects of the structure relaxation at the interface are fully considered, however, with the price of a high computational cost especially when the lattice mismatch is large . Therefore, the interface model is not suitable for the high-throughput computational screening of heterojunctions.…”