scholarly journals Asymmetric Schottky Contacts in van der Waals Metal-Semiconductor-Metal Structures Based on Two-Dimensional Janus Materials

Research ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Jia Liu ◽  
Ji-Chang Ren ◽  
Tao Shen ◽  
Xinyi Liu ◽  
Christopher J. Butch ◽  
...  
Keyword(s):  
Density Functional ◽  
Large Scale ◽  
Van Der Waals ◽  
Density Functional Theory Calculations ◽  
Practical Method ◽  
Asymmetric Structure ◽  
Fermi Level Pinning ◽  
Metal Semiconductor Metal ◽  
The Face ◽  
Msm Structure

Physical and electronic asymmetry plays a crucial role in rectifiers and other devices with a directionally variant current-voltage (I-V) ratio. Several strategies for practically creating asymmetry in nanoscale components have been demonstrated, but complex fabrication procedures, high cost, and incomplete mechanistic understanding have significantly limited large-scale applications of these components. In this work, we present density functional theory calculations which demonstrate asymmetric electronic properties in a metal-semiconductor-metal (MSM) interface composed of stacked van der Waals (vdW) heterostructures. Janus MoSSe has an intrinsic dipole due to its asymmetric structure and, consequently, can act as either an n-type or p-type diode depending on the face at the interior of the stacked structure (SeMoS-SMoS vs. SMoSe-SMoS). In each configuration, vdW forces dominate the interfacial interactions, and thus, Fermi level pinning is largely suppressed. Our transport calculations show that not only does the intrinsic dipole cause asymmetric I-V characteristics in the MSM structure but also that different transmission mechanisms are involved across the S-S (direct tunneling) and S-Se interface (thermionic excitation). This work illustrates a simple and practical method to introduce asymmetric Schottky barriers into an MSM structure and provides a conceptual framework which can be extended to other 2D Janus semiconductors.

scholarly journals Tensor-structured algorithm for reduced-order scaling large-scale Kohn–Sham density functional theory calculations

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Chih-Chuen Lin ◽  
Phani Motamarri ◽  
Vikram Gavini
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Large Scale ◽  
Density Functional Theory Calculations ◽  
System Size ◽  
Real Space ◽  
Functional Theory ◽  
Reduced Order ◽  
Separable Approximation ◽  
Tensor Basis

AbstractWe present a tensor-structured algorithm for efficient large-scale density functional theory (DFT) calculations by constructing a Tucker tensor basis that is adapted to the Kohn–Sham Hamiltonian and localized in real-space. The proposed approach uses an additive separable approximation to the Kohn–Sham Hamiltonian and an L1 localization technique to generate the 1-D localized functions that constitute the Tucker tensor basis. Numerical results show that the resulting Tucker tensor basis exhibits exponential convergence in the ground-state energy with increasing Tucker rank. Further, the proposed tensor-structured algorithm demonstrated sub-quadratic scaling with system-size for both systems with and without a gap, and involving many thousands of atoms. This reduced-order scaling has also resulted in the proposed approach outperforming plane-wave DFT implementation for systems beyond 2000 electrons.

scholarly journals Cross-plane transport in a single-molecule two-dimensional van der Waals heterojunction

2020 ◽  
Vol 6 (22) ◽  
pp. eaba6714 ◽  
Author(s):  
Shiqiang Zhao ◽  
Qingqing Wu ◽  
Jiuchan Pi ◽  
Junyang Liu ◽  
Jueting Zheng ◽  
...  
Keyword(s):  
Charge Transport ◽  
Single Molecule ◽  
Density Functional ◽  
Electronic Materials ◽  
2D Materials ◽  
Molecular Layer ◽  
Van Der Waals ◽  
Density Functional Theory Calculations ◽  
Two Dimensional ◽  
Guest Molecules

Two-dimensional van der Waals heterojunctions (2D-vdWHs) stacked from atomically thick 2D materials are predicted to be a diverse class of electronic materials with unique electronic properties. These properties can be further tuned by sandwiching monolayers of planar organic molecules between 2D materials to form molecular 2D-vdWHs (M-2D-vdWHs), in which electricity flows in a cross-plane way from one 2D layer to the other via a single molecular layer. Using a newly developed cross-plane break junction technique, combined with density functional theory calculations, we show that M-2D-vdWHs can be created and that cross-plane charge transport can be tuned by incorporating guest molecules. The M-2D-vdWHs exhibit distinct cross-plane charge transport signatures, which differ from those of molecules undergoing in-plane charge transport.

Optoelectronic and solar cell applications of Janus monolayers and their van der Waals heterostructures

2019 ◽  
Vol 21 (34) ◽  
pp. 18612-18621 ◽  
Author(s):  
M. Idrees ◽  
H. U. Din ◽  
R. Ali ◽  
G. Rehman ◽  
T. Hussain ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Solar Cell ◽  
Density Functional ◽  
Van Der Waals ◽  
Density Functional Theory Calculations ◽  
Hybrid Density Functional Theory ◽  
Van Der Waals Heterostructures ◽  
Functional Theory ◽  
Hybrid Density Functional

Janus monolayers and their van der Waals heterostuctures are investigated by hybrid density functional theory calculations.

Mass Spectrometry of Cyclopentadienylideneketene: Differentiation of Isomeric Ion Structures by Means of Ion/Molecule Reactions

2012 ◽  
Vol 65 (12) ◽  
pp. 1655 ◽  
Author(s):  
Pascal Gerbaux ◽  
Curt Wentrup
Keyword(s):  
Mass Spectrometry ◽  
Density Functional Theory ◽  
Density Functional ◽  
Large Scale ◽  
Density Functional Theory Calculations ◽  
Molecular Ions ◽  
Functional Theory ◽  
Clear Cut ◽  
Ion Molecule Reactions ◽  
Hybrid Mass Spectrometer

The nature of the m/z 104 ions formed by loss of CO2 or Ph-O-NCO from the molecular ions of phthalic anhydride, N-phenoxyphthalimide, and N-phenoxyisophthalimide was investigated by means of ion/molecule reactions with acetone. This allows a clear-cut differentiation of the so-obtained ions from the isomeric molecular ions of cyclopentadienylideneketene. The different intrinsic chemical reactivities of ionized cyclopentadienylideneketene and its distonoid isomer towards neutral acetone were investigated on a large-scale hybrid mass spectrometer and confirmed by density functional theory calculations.

scholarly journals A van der Waals density functional investigation of carboranethiol self-assembled monolayers on Au(111)

2016 ◽  
Vol 18 (18) ◽  
pp. 12920-12927 ◽  
Author(s):  
Ersen Mete ◽  
Ayşen Yılmaz ◽  
Mehmet Fatih Danışman
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Van Der Waals ◽  
Density Functional Theory Calculations ◽  
Self Assembled Monolayers ◽  
Functional Theory ◽  
Monolayer Adsorption ◽  
Assembled Monolayers ◽  
Self Assembled ◽  
Functional Investigation

Isolated and full monolayer adsorption of various carboranethiol (C2B10H12S) isomers on the gold(111) surface has been investigated using both the standard and van der Waals density functional theory calculations.

ADSORPTION OF THIOPHENE ON N-DOPED TiO2/MoS2 NANOCOMPOSITES INVESTIGATED BY VAN DER WAALS CORRECTED DENSITY FUNCTIONAL THEORY

2018 ◽  
Vol 25 (01) ◽  
pp. 1850038
Author(s):  
AMIRALI ABBASI ◽  
JABER JAHANBIN SARDROODI
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Van Der Waals ◽  
Titanium Atom ◽  
Density Functional Theory Calculations ◽  
Van Der Waals Interactions ◽  
Functional Theory ◽  
Structural And Electronic Properties ◽  
Potential Applicability ◽  
Thiophene Molecule

Comparison of structural and electronic properties between pristine and N-doped titanium dioxide-(TiO2)/molybdenum disulfide (MoS2) nanocomposites and their effects on the adsorption of thiophene molecule were performed using density functional theory calculations. To correctly estimate the adsorption energies, the van der Waals interactions were taken into account in the calculations. On the TiO2/MoS2 nanocomposite, thiophene molecule tends to be strongly adsorbed by its sulfur atom. The five-fold coordinated titanium atom of TiO2 was found to be an active binding site for thiophene adsorption. The results suggest that the thiophene molecule has not any mutual interaction with MoS2 nanosheet. The electronic structures of the complex systems are discussed in terms of the density of states and molecular orbitals of the thiophene molecules adsorbed to the TiO2/MoS2 nanocomposites. It was also found that the doping of nitrogen atom is conductive to the interaction of thiophene with nanocomposite. Thus, it can be concluded that the interaction of thiophene with N-doped TiO2/MoS2 nanocomposite is more energetically favorable than the interaction with undoped nanocomposite. The sensing capability of TiO2/MoS2 toward thiophene detection was greatly increased upon nitrogen doping. These processes ultimately lead to the strong adsorption of thiophene on the N-doped TiO2/MoS2 nanocomposites, indicating potential applicability of these nanocomposites as novel gas sensors.

scholarly journals Intriguing electronic, optical and photocatalytic performance of BSe, M2CO2 monolayers and BSe–M2CO2 (M = Ti, Zr, Hf) van der Waals heterostructures

RSC Advances ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 42-52
Author(s):  
M. Munawar ◽  
M. Idrees ◽  
Iftikhar Ahmad ◽  
H. U. Din ◽  
B. Amin
Keyword(s):  
Density Functional Theory ◽  
Band Structure ◽  
Density Functional ◽  
Photocatalytic Performance ◽  
Electronic Band Structure ◽  
Van Der Waals ◽  
Density Functional Theory Calculations ◽  
Van Der Waals Heterostructures ◽  
Electronic Band ◽  
Functional Theory

Using density functional theory calculations, we have investigated the electronic band structure, optical and photocatalytic response of BSe, M2CO2 (M = Ti, Zr, Hf) monolayers and their corresponding BSe–M2CO2 (M = Ti, Zr, Hf) van der Waals heterostructures.

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