12 results on '"Zhaoli Gao"'
Search Results
2. Curvature-Induced One-Dimensional Phonon Polaritons at Edges of Folded Boron Nitride Sheets
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Xingxu Yan, Jie Li, Lei Gu, Chaitanya Avinash Gadre, Samuel L. Moore, Toshihiro Aoki, Shuopei Wang, Guangyu Zhang, Zhaoli Gao, Dimitri N. Basov, Ruqian Wu, and Xiaoqing Pan
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Mechanical Engineering ,General Materials Science ,Bioengineering ,General Chemistry ,Condensed Matter Physics - Abstract
Generation and manipulation of phonon polaritons are of paramount importance for understanding the interaction between an electromagnetic field and dielectric materials and furthering their application in mid-infrared optical communication. However, the formation of tunable one-dimensional phonon polaritons has been rarely realized in van der Waals layered structures. Here we report the discovery of curvature-induced phonon polaritons localized at the crease of folded hexagonal boron nitrides (
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- 2022
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3. Aptasensors Based on Graphene Field-Effect Transistors for Arsenite Detection
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Jingwei Li, Abhishek Tyagi, Ting Huang, Hongwei Liu, Honglin Sun, Jiawen You, Md Masruck Alam, Xiangrong Li, and Zhaoli Gao
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General Materials Science - Published
- 2022
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4. Coherent Heterostructure Mesh Grown by Gap-Filling Epitaxial Chemical Vapor Deposition
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Hongwei Liu, Zhenjing Liu, Xiangbin Cai, Hoilun Wong, Meizhen Huang, Mohammadreza Amjadian, Jun Wang, Mohsen Tamtaji, Jingwei Li, Ting Kang, Tsz Wing Tang, Yuting Cai, Mengyang Xu, Kenan Zhang, Tao Xu, Mengjia Xu, Xudong Sun, Guojie Chen, Zhaoli Gao, Ning Wang, and Zhengtang Luo
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General Chemical Engineering ,Materials Chemistry ,General Chemistry - Published
- 2022
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5. Transmission-Matrix Quantitative Phase Profilometry for Accurate and Fast Thickness Mapping of 2D Materials
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Yujie Nie, Nansen Zhou, Li Tao, Jinlong Zhu, Zhaoli Gao, Jianbin Xu, and Renjie Zhou
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FOS: Physical sciences ,Applied Physics (physics.app-ph) ,Physics - Applied Physics ,Electrical and Electronic Engineering ,Atomic and Molecular Physics, and Optics ,Optics (physics.optics) ,Physics - Optics ,Biotechnology ,Electronic, Optical and Magnetic Materials - Abstract
The physical properties of two-dimensional (2D) materials may drastically vary with their thickness profiles. Current thickness profiling methods for 2D material (e.g., atomic force microscopy and ellipsometry) are limited in measurement throughput and accuracy. Here we present a novel high-speed and high-precision thickness profiling method, termed Transmission-Matrix Quantitative Phase Profilometry (TM-QPP). In TM-QPP, picometer-level optical pathlength sensitivity is enabled by extending the photon shot-noise limit of a high sensitivity common-path interferometric microscopy technique, while accurate thickness determination is realized by developing a transmission-matrix model that accounts for multiple refractions and reflections of light at sample interfaces. Using TM-QPP, the exact thickness profiles of monolayer and few-layered 2D materials (e.g., MoS2, MoSe2 and WSe2) are mapped over a wide field of view within seconds in a contact-free manner. Notably, TM-QPP is also capable of spatially resolving the number of layers of few-layered 2D materials.
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- 2023
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6. Origin of Nanoscale Friction Contrast between Supported Graphene, MoS2, and a Graphene/MoS2 Heterostructure
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A. T. Charlie Johnson, Zhaoli Gao, Alberto Otero-de-la-Roza, Ashlie Martini, Robert W. Carpick, Erin R. Johnson, Han Ye, Mohammad R. Vazirisereshk, Meng-Qiang Zhao, and Zhijiang Ye
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Materials science ,Normal force ,Condensed matter physics ,Graphene ,Atomic force microscopy ,Mechanical Engineering ,Bioengineering ,Heterojunction ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,law.invention ,Molecular dynamics ,law ,Monolayer ,General Materials Science ,Density functional theory ,0210 nano-technology ,Nanoscopic scale - Abstract
Ultralow friction can be achieved with 2D materials, particularly graphene and MoS2. The nanotribological properties of these different 2D materials have been measured in previous atomic force microscope (AFM) experiments sequentially, precluding immediate and direct comparison of their frictional behavior. Here, friction is characterized at the nanoscale using AFM experiments with the same tip sliding over graphene, MoS2, and a graphene/MoS2 heterostructure in a single measurement, repeated hundreds of times, and also measured with a slowly varying normal force. The same material systems are simulated using molecular dynamics (MD) and analyzed using density functional theory (DFT) calculations. In both experiments and MD simulations, graphene consistently exhibits lower friction than the MoS2 monolayer and the heterostructure. In some cases, friction on the heterostructure is lower than that on the MoS2 monolayer. Quasi-static MD simulations and DFT calculations show that the origin of the friction contrast is the difference in energy barriers for a tip sliding across each of the three surfaces.
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- 2019
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7. Crystalline Bilayer Graphene with Preferential Stacking from Ni–Cu Gradient Alloy
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Alan T. Johnson, Carl H. Naylor, Zhengtang Luo, Qicheng Zhang, Pedro Ducos, Jinglei Ping, Li Ren, Irfan Haider Abidi, Meng-Qiang Zhao, Youngkuk Kim, Zhaoli Gao, Jonathan Zauberman, and Andrew M. Rappe
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Materials science ,Precipitation (chemistry) ,Alloy ,General Engineering ,Stacking ,General Physics and Astronomy ,chemistry.chemical_element ,02 engineering and technology ,Substrate (electronics) ,engineering.material ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Copper ,0104 chemical sciences ,Crystallinity ,chemistry ,Chemical engineering ,engineering ,General Materials Science ,0210 nano-technology ,Bilayer graphene ,Single crystal - Abstract
We developed a high-yield synthesis of highly crystalline bilayer graphene (BLG) with two preferential stacking modes using a Ni-Cu gradient alloy growth substrate. Previously reported approaches for BLG growth include flat growth substrates of Cu or Ni-Cu uniform alloys and "copper pocket" structures. Use of flat substrates has the advantage of being scalable, but the growth mechanism is either "surface limited" (for Cu) or carbon precipitation (for uniform Ni-Cu), which results in multicrystalline BLG grains. For copper pockets, growth proceeds through a carbon back-diffusion mechanism, which leads to the formation of highly crystalline BLG, but scaling of the copper pocket structure is expected to be difficult. Here we demonstrate a Ni-Cu gradient alloy that combines the advantages of these earlier methods: the substrate is flat, so easy to scale, while growth proceeds by a carbon back-diffusion mechanism leading to high-yield growth of BLG with high crystallinity. The BLG layer stacking was almost exclusively Bernal or twisted with an angle of 30°, consistent with first-principles calculations we conducted. Furthermore, we demonstrated scalable production of transistor arrays based crystalline Bernal-stacked BLG with a band gap that was tunable at room temperature.
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- 2018
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8. New Approach to Unveiling Individual Atomic Layers of 2D Materials and Their Heterostructures
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Zhengtang Luo, Yao Ding, Irfan Haider Abidi, Xuewu Ou, Lin Gan, Lu-Tao Weng, Man li, Minghao Zhuang, Abhishek Tyagi, Chi Pui Jeremy Wong, Delowar Hossain, Zhaoli Gao, and Ruiwen Xue
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Materials science ,Graphene ,General Chemical Engineering ,Heterojunction ,Nanotechnology ,Hexagonal boron nitride ,02 engineering and technology ,General Chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Atomic units ,0104 chemical sciences ,law.invention ,Secondary ion mass spectrometry ,Interference (communication) ,Transition metal ,law ,Chemical specificity ,Materials Chemistry ,0210 nano-technology - Abstract
Visualization of the chemical structures of two-dimensional (2D) materials and their interfaces at the virtually atomic scale is an imperative step toward devising highly efficient ultrathin optoelectronic devices. Herein, we demonstrate a universal method featuring time-of-flight secondary ion mass spectrometry (ToF-SIMS), coupled with the structure simplicity of 2D materials, as a versatile tool to reveal the vertical atomic layers of various two-dimensional (2D) materials including graphene, hexagonal boron nitride (h-BN), and transition metal dichalcogenides (TMDs). We demonstrated that the vertical atomic layers of those 2D materials can be unveiled layer-by-layer using a strategy of ToF-SIMS three-dimensional (3D) analysis developed in this work. Moreover, we found that the extreme surface sensitivity and chemical specificity of ToF-SIMS also enables the examination of the lateral uniformity of 2D materials. During this process, we first removed interference of adsorbed organic contamination by anne...
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- 2018
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9. Recoil Effect and Photoemission Splitting of Trions in Monolayer MoS2
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Qicheng Zhang, Minghao Zhuang, Aldrine Abenoja Cagang, Zhengtang Luo, Ruizhe Wu, Meng-Qiang Zhao, Irfan Haider Abidi, Yao Ding, Xuewu Ou, Zhaoli Gao, and Carl H. Naylor
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Photoluminescence ,Condensed Matter::Other ,Chemistry ,Exciton ,Fermi level ,General Engineering ,General Physics and Astronomy ,02 engineering and technology ,Photon energy ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,021001 nanoscience & nanotechnology ,01 natural sciences ,Condensed Matter::Materials Science ,symbols.namesake ,Recoil ,0103 physical sciences ,Monolayer ,Bound state ,symbols ,Condensed Matter::Strongly Correlated Electrons ,General Materials Science ,Atomic physics ,Trion ,010306 general physics ,0210 nano-technology - Abstract
The 2D geometry nature and low dielectric constant in transition-metal dichalcogenides lead to easily formed strongly bound excitons and trions. Here, we studied the photoluminescence of van der Waals heterostructures of monolayer MoS2 and graphene at room temperature and observed two photoluminescence peaks that are associated with trion emission. Further study of different heterostructure configurations confirms that these two peaks are intrinsic to MoS2 and originate from a bound state and Fermi level, respectively, of which both accept recoiled electrons from trion recombination. We demonstrate that the recoil effect allows us to electrically control the photon energy of trion emission by adjusting the gate voltage. In addition, significant thermal smearing at room temperature results in capture of recoil electrons by bound states, creating photoemission peak at low doping level whose photon energy is less sensitive to gate voltage tuning. This discovery reveals an unexpected role of bound states for ...
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- 2017
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10. Synthesis and Physical Properties of Phase-Engineered Transition Metal Dichalcogenide Monolayer Heterostructures
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Carl H. Naylor, Qicheng Zhang, William M. Parkin, Andrew M. Rappe, Liang Z. Tan, Zhaoli Gao, Songsong Zhou, Ram Surya Gona, Marija Drndic, Joel Berry, Robert W. Carpick, Meng-Qiang Zhao, J. B. McClimon, Christopher E. Kehayias, David J. Srolovitz, and Alan T. Johnson
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Materials science ,Field (physics) ,General Engineering ,General Physics and Astronomy ,Nanotechnology ,Heterojunction ,02 engineering and technology ,Chemical vapor deposition ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,symbols.namesake ,Transition metal ,Transmission electron microscopy ,Chemical physics ,Phase (matter) ,Monolayer ,symbols ,General Materials Science ,0210 nano-technology ,Raman spectroscopy - Abstract
Heterostructures of transition metal dichalcogenides (TMDs) offer the attractive prospect of combining distinct physical properties derived from different TMD structures. Here, we report direct chemical vapor deposition of in-plane monolayer heterostructures based on 1H-MoS2 and 1T′-MoTe2. The large lattice mismatch between these materials led to intriguing phenomena at their interface. Atomic force microscopy indicated buckling in the 1H region. Tip-enhanced Raman spectroscopy showed mode structure consistent with Te substitution in the 1H region during 1T′-MoTe2 growth. This was confirmed by atomic resolution transmission electron microscopy, which also revealed an atomically stitched, dislocation-free 1H/1T′ interface. Theoretical modeling revealed that both the buckling and absence of interfacial misfit dislocations were explained by lateral gradients in Te substitution levels within the 1H region and elastic coupling between 1H and 1T′ domains. Phase field simulations predicted 1T′ morphologies with ...
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- 2017
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11. Monolayer Single-Crystal 1T′-MoTe2 Grown by Chemical Vapor Deposition Exhibits Weak Antilocalization Effect
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Andrew M. Rappe, William M. Parkin, A. T. Charlie Johnson, Marija Drndic, Yu Ren Zhou, Youngkuk Kim, James M. Kikkawa, Robert W. Carpick, Carl H. Naylor, Zhaoli Gao, Frank Streller, and Jinglei Ping
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Bioengineering ,02 engineering and technology ,Chemical vapor deposition ,Spectrum Analysis, Raman ,010402 general chemistry ,01 natural sciences ,Article ,Condensed Matter::Materials Science ,symbols.namesake ,Transition metal ,X-ray photoelectron spectroscopy ,Monolayer ,Topological order ,General Materials Science ,Condensed matter physics ,Chemistry ,Photoelectron Spectroscopy ,Mechanical Engineering ,Temperature ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,0104 chemical sciences ,Cold Temperature ,Topological insulator ,symbols ,Gases ,0210 nano-technology ,Raman spectroscopy ,Single crystal - Abstract
Growth of transition metal dichalcogenide (TMD) monolayers is of interest due to their unique electrical and optical properties. Films in the 2H and 1T phases have been widely studied but monolayers of some 1T'-TMDs are predicted to be large-gap quantum spin Hall insulators, suitable for innovative transistor structures that can be switched via a topological phase transition rather than conventional carrier depletion [ Qian et al. Science 2014 , 346 , 1344 - 1347 ]. Here we detail a reproducible method for chemical vapor deposition of monolayer, single-crystal flakes of 1T'-MoTe2. Atomic force microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy confirm the composition and structure of MoTe2 flakes. Variable temperature magnetotransport shows weak antilocalization at low temperatures, an effect seen in topological insulators and evidence of strong spin-orbit coupling. Our approach provides a pathway to systematic investigation of monolayer, single-crystal 1T'-MoTe2 and implementation in next-generation nanoelectronic devices.
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- 2016
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12. Growth of Vertically Aligned Carbon Nanotube Arrays on Al Substrates through Controlled Diffusion of Catalyst
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Kai Zhang, Xin Zhang, Matthew Ming Fai Yuen, and Zhaoli Gao
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inorganic chemicals ,Materials science ,organic chemicals ,Diffusion ,chemistry.chemical_element ,Nanotechnology ,Substrate (electronics) ,Carbon nanotube ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Catalysis ,law.invention ,Atomic diffusion ,General Energy ,chemistry ,Chemical engineering ,Aluminium ,law ,heterocyclic compounds ,Grain boundary ,Physical and Theoretical Chemistry ,Thin film - Abstract
Atomic diffusion-induced catalyst evolution affects the iron catalyst lifetime and the collective termination of VACNT growth on a metal substrate. We demonstrated that controlled catalyst diffusion in the pretreatment stage is capable of extending the iron catalyst lifetime on an aluminum thin-film substrate to allow enhanced vertically aligned carbon nanotube (VACNT) growth by a conventional low-pressure thermal chemical vapor deposition. In adopting a fast-heating pretreatment to control the catalyst loss from diffusion, catalyst lifetime was extended, leading to the VACNT growth with heights up to 65% taller than those without the diffusion control strategy. Atomic diffusion of iron catalyst along the grain boundaries of aluminum thin films was found to play a critical role in the catalyst loss mechanism. This work provides the basic understanding of catalyst diffusion control to facilitate the growth of VACNT arrays on metallic substrates for various applications such as through silicon via interconn...
- Published
- 2015
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