Publications (44)
Elastomeric waveguide on-chip coupling of an encapsulated MoS monolayer
Filip Auksztol, Daniele Vella, Ivan Verzhbitskiy +6
We propose a robust photonic platform for encapsulation and addressing of optically active 2D- and nano-materials. Our implementation utilises a monolayer of MoS transition met…
Microstructure and Elastic Constants of Transition Metal Dichalcogenide Monolayers from Friction and Shear Force Microscopy
Xiaomin Xu, Thorsten Schultz, Ziyu Qin +10
Optical and electrical properties of two-dimensional transition metal dichalcogenides (TMDCs) grown by chemical vapor deposition (CVD) are strongly determined by their microstructu…
Mode-center Placement of Monolayer WS in a Photonic Polymer Waveguide
Angelina Frank, Justin Zhou, James A. Grieve +8
Effective integration of 2D materials such as monolayer transition metal dichalcogenides (TMDs) into photonic waveguides and integrated circuits is being intensely pursued due to t…
Insulator to semi-metal transition in graphene oxide
Goki Eda, Cecilia Mattevi, Hisato Yamaguchi +2
Transport properties of progressively reduced graphene oxide (GO) are described. Evolution of the electronic properties reveals that as-synthesized GO undergoes insulator-semicondu…
Valence band electronic structure evolution of graphene oxide upon thermal annealing for optoelectronics
Hisato Yamaguchi, Shuichi Ogawa, Daiki Watanabe +19
We report valence band electronic structure evolution of graphene oxide (GO) upon its thermal reduction. Degree of oxygen functionalization was controlled by annealing temperatures…
Vapor-Liquid-Solid Growth of Monolayer MoS2 Nanoribbons
Shisheng Li, Yung-Chang Lin, Wen Zhao +19
Chemical vapor deposition (CVD) of two-dimensional (2D) materials such as monolayer MoS2 typically involves the conversion of vapor-phase precursors to a solid product in a process…
Enhanced Catalytic Activity in Strained Chemically Exfoliated WS2 Nanosheets for Hydrogen Evolution
Damien Voiry, Hisato Yamaguchi, Junwen Li +8
The ability to efficiently evolve hydrogen via electrocatalysis at low overpotentials holds tremendous promise for clean energy. Hydrogen evolution reaction (HER) can be easily ach…
Nonlinear magnetotransport shaped by Fermi surface topology and convexity in WTe2
Pan He, Chuang-Han Hsu, Shuyuan Shi +7
The nature of Fermi surface defines the physical properties of conductors and many physical phenomena can be traced to its shape. Although the recent discovery of a current-depende…
Evidence for Fast Interlayer Energy Transfer in MoSe2/WS2 Heterostructures
Daichi Kozawa, Alexandra Carvalho, Ivan Verzhbitskiy +6
Strongly bound excitons confined in two-dimensional (2D) semiconductors are dipoles with a perfect in-plane orientation. In a vertical stack of semiconducting 2D crystals, such in-…
Strain-Mediated Lattice Reconstruction Enhances Ferromagnetism in Cr2Ge2Te6/WTe2 van der Waals Heterobilayers
Franz Herling, Mireia Torres-Sala, Dorye L. Esteras +17
Van der Waals (vdW) heterostructures enable tailored electronic and magnetic phases by stacking atomically thin layers with pristine interfaces. Here, we investigate fully 2D Cr2Ge…
Evolution of Electronic Structure in Atomically Thin Sheets of WS2 and WSe2
Weijie Zhao, Zohreh Ghorannevis, Leiqiang Chua +4
Geometrical confinement effect in exfoliated sheets of layered materials leads to significant evolution of energy dispersion with decreasing layer thickness. Molybdenum disulphide…
Charge transport in ion-gated mono-, bi-, and trilayer MoS2 field effect transistors
Leiqiang Chu, Hennrik Schmidt, Jiang Pu +4
Charge transport in MoS2 in the low carrier density regime is dominated by trap states and band edge disorder. The intrinsic transport properties of MoS2 emerge in the high density…
Engineering bandgaps of monolayer MoS2 and WS2 on fluoropolymer substrates by electrostatically tuned many-body effects
Bo Liu, Weijie Zhao, Zijing Ding +6
Intrinsic electrical and excitonic properties of monolayer transition metal dichalcogenides are studied on CYTOP fluoropolymer substrates with greatly suppressed unintentional dopi…
Suppressed out-of-plane polarizability of free excitons in monolayer WSe
Ivan A. Verzhbitskiy, Daniele Vella, Kenji Watanabe +2
Monolayer semiconductors are atomically thin quantum wells with strong confinement of electrons in two-dimensional (2D) plane. Here, we experimentally study the out-of-plane polari…
Highly Uniform 300 mm Wafer-Scale Deposition of Single and Multilayered Chemically Derived Graphene Thin Films
Hisato Yamaguchi, Goki Eda, Cecilia Mattevi +2
The deposition of atomically thin highly uniform chemically derived graphene (CDG) films on 300 mm SiO2/Si wafers is reported. We demonstrate that the very thin films can be lifted…
Probing spin dynamics of ultra-thin van der Waals magnets via photon-magnon coupling
Christoph W. Zollitsch, Safe Khan, Vu Thanh Trung Nam +9
Layered van der Waals (vdW) magnets can maintain a magnetic order even down to the single-layer regime and hold promise for integrated spintronic devices. While the magnetic ground…
Photocarrier relaxation in two-dimensional semiconductors
Daichi Kozawa, Rajeev Kumar, Alexandra Carvalho +8
Two-dimensional (2D) crystals of semiconducting transition metal dichalcogenides (TMD) absorb a large fraction of incident photons in the visible frequencies despite being atomical…
Characterization of the second- and third-harmonic optical susceptibilities of atomically thin tungsten diselenide
Henrique G. Rosa, Ho Yi Wei, Ivan Verzhbitskiy +6
We report the first detailed characterization of the sheet third-harmonic optical susceptibility, , of tungsten diselenide (WSe). With a home-built confocal mic…
Enhancing charge-density-wave order in 1T-TiSe2 nanosheet by encapsulation with hexagonal Boron Nitride
Linjun Li, WeiJie Zhao, Bo Liu +3
Layered transition metal dichalcogenides (TMDs) provide an ideal platform for exploring the effects of dimensionality on correlated electronic phases such as charge density wave (C…
Halide-Assisted Atmospheric Pressure Growth of Large WSe2 and WS2 Monolayer Crystals
Shisheng Li, Shunfeng Wang, Dai-Ming Tang +6
Chemical vapor deposition (CVD) of two-dimensional (2D) tungsten dichalcogenide crystals requires steady flow of tungsten source in the vapor phase. This often requires high temper…
Context-Aware Deep Learning for Defect Classification in Atomic-Resolution STEM
Jiadong Dan, Cheng Zhang, Leyi Loh +5
Artificial intelligence is rapidly advancing materials characterization, yet most applications in electron microscopy rely solely on image contrast, overlooking the chemical and ex…
Tailoring Magnetic Anisotropy in CrGeTe by Electrostatic Gating
Ivan. A. Verzhbitskiy, Hidekazu Kurebayashi, Haixia Cheng +4
Electrical control of magnetism of a ferromagnetic semiconductor offers exciting prospects for future spintronic devices for processing and storing information. Here, we report obs…
Ultrathin quantum light source enabled by a nonlinear van der Waals crystal with vanishing interlayer-electronic-coupling
Qiangbing Guo, Xiao-Zhuo Qi, Meng Gao +19
Interlayer electronic coupling in two-dimensional (2D) materials enables tunable and emergent properties by stacking engineering. However, it also brings significant evolution of e…
Nonlinear Photoluminescence in Atomically Thin Layered WSe2 Arising from Diffusion-Assisted Exciton-Exciton Annihilation
Shinichiro Mouri, Yuhei Miyauchi, Minglin Toh +3
We studied multi-exciton dynamics in monolayer WSe2 using nonlinear photoluminescence (PL) spectroscopy and Monte Carlo simulations. We observed strong nonlinear saturation behavio…
Reply to: Mobility overestimation in MoS transistors due to invasive voltage probes
Hong Kuan Ng, Du Xiang, Ady Suwardi +17
In this reply, we include new experimental results and verify that the observed non-linearity in rippled-MoS (leading to mobility kink) is an intrinsic property of a disordered…
Topological Weyl phase transition in MoWTe
Ilya Belopolski, Daniel S. Sanchez, Yukiaki Ishida +21
Topological phases of matter exhibit phase transitions between distinct topological classes. These phase transitions are exotic in that they do not fall within the traditional Ginz…
Spin-Orbit Proximity Effect in Graphene
Ahmet Avsar, Jun You Tan, Jayakumar Balakrishnan +9
The development of a spintronics device relies on efficient generation of spin polarized currents and their electric field controlled manipulation. While observation of exceptional…
Laser-induced topological spin switching in a 2D van der Waals magnet
Maya Khela, Maciej Dabrowski, Safe Khan +6
Two-dimensional (2D) van der Waals (vdW) magnets represent one of the most promising horizons for energy-efficient spintronic applications because their broad range of electronic,…
Lattice dynamics in mono- and few-layer sheets of WS2 and WSe2
Weijie Zhao, Zohreh Ghorannevis, Amara Kiran Kumar +6
Thickness is one of the fundamental parameters that define the electronic, optical, and thermal properties of two-dimensional (2D) crystals. Phonons in molybdenum disulfide (MoS2)…
An innovative way of etching MoS2: Characterization and mechanistic investigation
Yuan Huang, Jing Wu, Xiangfan Xu +9
We report a systematic study of the etching of MoS2 crystals by using XeF2 as a gaseous reactant. By controlling the etching process, monolayer MoS2 with uniform morphology can be…
Blue photoluminescence from chemically derived graphene oxide
Goki Eda, Yun-Yue Lin, Cecilia Mattevi +5
Fluorescent organic compounds are of significant importance to the development of low-cost opto-electronic devices. Blue fluorescence from aromatic or olefinic molecules and their…
Controlling many-body states by the electric-field effect in a two-dimensional material
Linjun Li, Eoin C. T. O Farrell, Kianping Loh +3
To understand complex physics of a system with strong electron electron interactions, it is ideal to control and monitor its properties while tuning an external electric field appl…
Room temperature nonlinear Hall effect and wireless RF rectification in Weyl semimetal TaIrTe4
Dushyant Kumar, Chuang-Han Hsu, Raghav Sharma +6
The nonlinear Hall effect (NLHE), which can produce a transverse voltage without any magnetic field, is a potential alternative for rectification or frequency doubling. However, th…
Data-driven discovery of high performance layered van der Waals piezoelectric NbOI2
Yaze Wu, Ibrahim Abdelwahab, Ki Chang Kwon +8
Using high-throughput first-principles calculations to search for layered van der Waals materials with the largest piezoelectric stress coefficients, we discover NbOI2 to be the on…
Observation of the out-of-plane polarized spin current from CVD grown WTe2
Shuyuan Shi, Jie Li, Chuang-Han Hsu +11
Weyl semimetal Td-phase WTe2 possesses the spin-resolved band structure with strong spin-orbit coupling, holding promises as a useful spin source material. The noncentrosymmetric c…
Origin of indirect optical transitions in few-layer MoS2, WS2 and WSe2
Weijie Zhao, R. M. Ribeiro, Minglin Toh +4
It has been well established that single layer MX2 (M=Mo,W and X=S,Se) are direct gap semiconductors with band edges coinciding at the K point in contrast to their indirect gap mul…
Large Thermoelectricity via Variable Range Hopping in Chemical Vapor Deposition Grown Single-layer MoS2
Jing Wu, Hennrik Schmidt, Amara Kiran Kumar +3
Ultrathin layers of semiconducting molybdenum disulfide (MoS2) offer significant prospects in future electronic and optoelectronic applications. Although an increasing number of ex…
Phase coherent transport in bilayer and trilayer MoS2
Leiqiang Chu, Indra Yudhistira, Hennrik Schmidt +3
Bilayer MoS2 is a centrosymmetric semiconductor with degenerate spin states in the six valleys at the corners of the Brillouin zone. It has been proposed that breaking of this inve…
Transport properties of monolayer MoS grown by chemical vapour deposition
Hennrik Schmidt, Shunfeng Wang, Leiqiang Chu +8
Recent success in the growth of monolayer MoS via chemical vapor deposition (CVD) has opened up prospects for the implementation of these materials into thin film electronic an…
Harnessing Exciton-Exciton Annihilation in Two-Dimensional Semiconductors
Eric Linardy, Dinesh Yadav, Daniele Vella +6
Strong many-body interactions in two-dimensional (2D) semiconductors give rise to efficient exciton-exciton annihilation (EEA). This process is expected to result in the generation…
Discovery of a new type of topological Weyl fermion semimetal state in MoWTe
Ilya Belopolski, Daniel S. Sanchez, Yukiaki Ishida +23
The recent discovery of a Weyl semimetal in TaAs offers the first Weyl fermion observed in nature and dramatically broadens the classification of topological phases. However, in Ta…
Ferroelectric brightening of spin forbidden dark excitons in a WSe2/hybrid perovskite heterostructure
Xinyun Wang, Magdalena Grzeszczyk, Maxim Trushin +14
Long-lived dark excitons in monolayer WSe2 present promising candidates for carrying spin and valley information, but their optical access and spin manipulation have conventionally…
Measuring valley polarization in two-dimensional materials with second-harmonic spectroscopy
Yi Wei Ho, Henrique Guimarães Rosa, Ivan Verzhbitskiy +6
A population imbalance at different valleys of an electronic system lowers its effective rotational symmetry. We introduce a technique to measure such imbalance - a valley polariza…
Field emission from atomically thin edges of reduced graphene oxide
Hisato Yamaguchi, Katsuhisa Murakami, Goki Eda +13
Point sources exhibit low threshold electron emission due to local field enhancement at the tip. The development and implementation of tip emitters have been hampered by the need t…