Heteroepitaxial van der Waals semiconductor superlattices

Abstract We report atomic layer-by-layer epitaxial growth of van der Waals (vdW) semiconductor superlattices (SLs) with programmable stacking periodicities, composed of more than two kinds of dissimilar transition-metal dichalcogenide monolayers (MLs), such as MoS2, WS2 and WSe2. The kinetics-controlled vdW epitaxy in the near equilibrium limit by metalorganic chemical vapour depositions enables to achieve accurate ML-by-ML stacking, free of interlayer atomic mixing, resulting in the tunable two-dimensional (2D) vdW electronic systems. We identified coherent atomic stacking orders at the vdW heterointerfaces, and present scaling valley polarized optical excitations that only pertain to a series of 2D type II band alignments.

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Disassembling 2D van der Waals crystals into macroscopic monolayers and reassembling into artificial lattices

Science ◽

10.1126/science.aba1416 ◽

2020 ◽

Vol 367 (6480) ◽

pp. 903-906 ◽

Cited By ~ 36

Author(s):

Fang Liu ◽

Wenjing Wu ◽

Yusong Bai ◽

Sang Hoon Chae ◽

Qiuyang Li ◽

...

Keyword(s):

Mass Production ◽

Van Der Waals ◽

Great Promise ◽

Layer By Layer ◽

Transition Metal Dichalcogenide ◽

High Quality ◽

Quantum Devices ◽

Artificial Materials ◽

Two Dimensional Materials ◽

One Step

Two-dimensional materials from layered van der Waals (vdW) crystals hold great promise for electronic, optoelectronic, and quantum devices, but technological implementation will be hampered by the lack of high-throughput techniques for exfoliating single-crystal monolayers with sufficient size and high quality. Here, we report a facile method to disassemble vdW single crystals layer by layer into monolayers with near-unity yield and with dimensions limited only by bulk crystal sizes. The macroscopic monolayers are comparable in quality to microscopic monolayers from conventional Scotch tape exfoliation. The monolayers can be assembled into macroscopic artificial structures, including transition metal dichalcogenide multilayers with broken inversion symmetry and substantially enhanced nonlinear optical response. This approach takes us one step closer to mass production of macroscopic monolayers and bulk-like artificial materials with controllable properties.

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Rheed Studies of a-Axis Oriented DyBa2Cu3O7 Films Grown by All-MBE

MRS Proceedings ◽

10.1557/proc-502-221 ◽

1997 ◽

Vol 502 ◽

Author(s):

Ivan Bozovic ◽

J. N. Eckstein ◽

Natasha Bozovic ◽

J. O'Donnell

Keyword(s):

Phase Transitions ◽

Secondary Phase ◽

Atomic Layer ◽

High Energy ◽

Layer By Layer ◽

Growth Modes ◽

Flow Surface ◽

Surface Phase Transitions

ABSTRACTReal-time, in-situ surface monitoring by reflection high-energy electron diffraction (RHEED) has been the key enabling component of atomic-layer-by-layer molecular beam epitaxy (ALL-MBE) of complex oxides. RHEED patterns contain information on crystallographic arrangements and long range order on the surface; this can be made quantitative with help of numerical simulations. The dynamics of RHEED patterns and intensities reveal a variety of phenomena such as nucleation and dissolution of secondary-phase precipitates, switching between growth modes (layer-by-layer, step-flow), surface phase transitions (surface reconstruction, roughening, and even phase transitions induced by the electron beam itself), etc. Some of these phenomena are illustrated here, using as a case study our recent growth of atomically smooth a-axis oriented DyBa2Cu3O7 films.

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Exciton-exciton interaction in transition metal dichalcogenide monolayers and van der Waals heterostructures

Physical Review B ◽

10.1103/physrevb.103.045426 ◽

2021 ◽

Vol 103 (4) ◽

Author(s):

Daniel Erkensten ◽

Samuel Brem ◽

Ermin Malic

Keyword(s):

Transition Metal ◽

Van Der Waals ◽

Transition Metal Dichalcogenide ◽

Van Der Waals Heterostructures ◽

Exciton Interaction

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Layer-by-Layer Molecular Assemblies for Dye-Sensitized Photoelectrosynthesis Cells Prepared by Atomic Layer Deposition

Journal of the American Chemical Society ◽

10.1021/jacs.7b07216 ◽

2017 ◽

Vol 139 (41) ◽

pp. 14518-14525 ◽

Cited By ~ 30

Author(s):

Degao Wang ◽

Matthew V. Sheridan ◽

Bing Shan ◽

Byron H. Farnum ◽

Seth L. Marquard ◽

...

Keyword(s):

Atomic Layer Deposition ◽

Atomic Layer ◽

Layer By Layer ◽

Molecular Assemblies ◽

Dye Sensitized ◽

Layer Deposition

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Rapid Thermal Processing-Based Heteroepitaxy: Material and Device Challenges

MRS Proceedings ◽

10.1557/proc-387-299 ◽

1995 ◽

Vol 387 ◽

Author(s):

J. L. Hoyt ◽

P. Kuo ◽

K. Rim ◽

J. J. Welser ◽

R. M. Emerson ◽

...

Keyword(s):

Thermal Processing ◽

Rapid Thermal Processing ◽

Atomic Layer ◽

Layer Growth ◽

Point Of View ◽

Atomic Layer Epitaxy ◽

Future Research ◽

Layer By Layer ◽

Limited Growth ◽

Measurement And Control

AbstractMaterial and device challenges for Rapid Thermal Processing (RTP) of heterostructures are discussed, focusing on RTP-based epitaxy in the Si/Si1−xGex system. While RTP-based heteroepitaxy offers enhanced processing flexibility, it also poses significant challenges for temperature measurement and control. Several examples of Si/Si1−xGex device structures are discussed from the point of view of the sensitivity of device parameters to variations in layer thickness and composition. The measured growth kinetics for Si and Si1−xGex are then used to estimate growth temperature tolerances for these structures. Demanding applications are expected to require temperature control and uniformity to within 0.5°C.Future research challenges include the fabrication of structures with monolayer thickness control using self-limited growth techniques. Atomic layer epitaxy (ALE) is a well-known example of such a growth technique. In ALE, the wafer is cyclically exposed to different reactants, to achieve layer-by-layer growth. An RTP-based atomic layer epitaxy process, and its application to the growth of CdTe films, is briefly discussed. The extension to Column IV alloys follows readily. The RTP-based process enables self-limited growth for precursor combinations for which isothermal ALE is not feasible.

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Atomic layer-by-layer construction of Pd on nanoporous gold via underpotential deposition and displacement reaction

RSC Advances ◽

10.1039/c4ra17014h ◽

2015 ◽

Vol 5 (25) ◽

pp. 19409-19417 ◽

Cited By ~ 19

Author(s):

Xuejiao Yan ◽

Haiyan Xiong ◽

Qingguo Bai ◽

Jan Frenzel ◽

Conghui Si ◽

...

Keyword(s):

Atomic Layer ◽

Underpotential Deposition ◽

Nanoporous Gold ◽

Layer By Layer ◽

Displacement Reaction ◽

Galvanic Displacement

Ultrathin Pd films with one to five atomic layers were decorated on nanoporous gold by underpotential deposition and galvanic displacement.

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Nanotribology of transition metal dichalcogenide flakes deposited by chemical vapour deposition: The influence of chemical composition and sliding speed on nanoscale friction of monolayers

Applied Surface Science ◽

10.1016/j.apsusc.2021.149762 ◽

2021 ◽

Vol 556 ◽

pp. 149762

Author(s):

Ales Rapuc ◽

He Wang ◽

Tomas Polcar

Keyword(s):

Chemical Composition ◽

Transition Metal ◽

Chemical Vapour Deposition ◽

Vapour Deposition ◽

Chemical Vapour ◽

Transition Metal Dichalcogenide ◽

Sliding Speed ◽

Nanoscale Friction

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Study of photogenerated exciton dissociation in transition metal dichalcogenide van der Waals heterojunction A2-MWS4: A first-principle study

Physical Chemistry Chemical Physics ◽

10.1039/d1cp03857e ◽

2021 ◽

Author(s):

Hong Cui ◽

yazhou wang ◽

Tong Liu ◽

Yunjian Chen ◽

Pengyue Shan ◽

...

Keyword(s):

Hydrogen Production ◽

Transition Metal ◽

Production Efficiency ◽

Van Der Waals ◽

Transition Metal Dichalcogenide ◽

First Principle ◽

Exciton Dissociation ◽

Photocatalytic Hydrogen Production

In order to explore the photocatalytic hydrogen production efficiency of MoS2/WSe2 heterostructure (A2-MWS4) as photocatalysts, It is highly desirable to study the photogenerated exciton dissociation related to photocatalysis. The electronic...

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Structural and Optical Properties of Luminescent Copper(I) Chloride Thin Films Deposited by Sequentially Pulsed Chemical Vapour Deposition

Coatings ◽

10.3390/coatings8100369 ◽

2018 ◽

Vol 8 (10) ◽

pp. 369 ◽

Cited By ~ 1

Author(s):

Richard Krumpolec ◽

Tomáš Homola ◽

David Cameron ◽

Josef Humlíček ◽

Ondřej Caha ◽

...

Keyword(s):

Atomic Layer Deposition ◽

Chemical Vapour Deposition ◽

Photoelectron Spectroscopy ◽

Vapour Deposition ◽

Chemical Vapour ◽

Atomic Layer ◽

Nanocrystalline Films ◽

Zinc Blende ◽

Layer Deposition

Sequentially pulsed chemical vapour deposition was used to successfully deposit thin nanocrystalline films of copper(I) chloride using an atomic layer deposition system in order to investigate their application to UV optoelectronics. The films were deposited at 125 °C using [Bis(trimethylsilyl)acetylene](hexafluoroacetylacetonato)copper(I) as a Cu precursor and pyridine hydrochloride as a new Cl precursor. The films were analysed by XRD, X-ray photoelectron spectroscopy (XPS), SEM, photoluminescence, and spectroscopic reflectance. Capping layers of aluminium oxide were deposited in situ by ALD (atomic layer deposition) to avoid environmental degradation. The film adopted a polycrystalline zinc blende-structure. The main contaminants were found to be organic materials from the precursor. Photoluminescence showed the characteristic free and bound exciton emissions from CuCl and the characteristic exciton absorption peaks could also be detected by reflectance measurements.

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