A5100706426- 2D Materials and Applications
- Graphene research and applications
- Advanced Sensor and Energy Harvesting Materials
- Advanced MEMS and NEMS Technologies
- MXene and MAX Phase Materials
- Carbon Nanotubes in Composites
- Perovskite Materials and Applications
- Adaptive optics and wavefront sensing
- Advanced Surface Polishing Techniques
- Microfluidic and Capillary Electrophoresis Applications
- Anodic Oxide Films and Nanostructures
- Nanowire Synthesis and Applications
- Chalcogenide Semiconductor Thin Films
- Electrohydrodynamics and Fluid Dynamics
- Force Microscopy Techniques and Applications
- Conducting polymers and applications
- Surface Modification and Superhydrophobicity
- Supercapacitor Materials and Fabrication
- Analytical Chemistry and Sensors
- Mechanical and Optical Resonators
- Electrowetting and Microfluidic Technologies
- Superconducting and THz Device Technology
- Cosmology and Gravitation Theories
- Nanopore and Nanochannel Transport Studies
- Molecular Junctions and Nanostructures
Stevens Institute of Technology
2016-2025
Stanford University
2002-2024
New York University
2022
California Institute of Technology
2003-2009
Institute of Science and Technology
2009
Jet Propulsion Laboratory
2000-2006
Ajou University
1995-2005
The University of Tokyo
1998-2002
Laboratory for Integrated Micro-Mechatronic Systems
2002
Tokyo University of Science
2002
Abstract Two-dimensional semiconductors, including transition metal dichalcogenides, are of interest in electronics and photonics but remain nonmagnetic their intrinsic form. Previous efforts to form two-dimensional dilute magnetic semiconductors utilized extrinsic doping techniques or bulk crystal growth, detrimentally affecting uniformity, scalability, Curie temperature. Here, we demonstrate an situ substitutional Fe atoms into MoS 2 monolayers the chemical vapor deposition growth. The...
This paper describes the fabrication and characterization of a hybrid nanostructure comprised carbon nanotubes (CNTs) grown on graphene layers for supercapacitor applications. The entire (CNTs graphene) was fabricated via atmospheric pressure chemical vapor deposition (APCVD) designed to minimize self-aggregation CNTs. Growth parameters CNTs were optimized by adjusting gas flow rates hydrogen methane control simultaneous, competing reactions formation toward CNT growth hydrogenation which...
We describe a facile technique based on polymer encapsulation to apply several percent controllable strains monolayer and few-layer Transition Metal Dichalcogenides (TMDs). use this study the lattice response strain via polarized Raman spectroscopy in WSe2 WS2. The application of causes mode-dependent redshifts, with larger shift rates observed for in-plane modes. observe splitting degeneracy E' modes both materials measure Gruneisen parameters. At large strain, we that reduction crystal...
Monolayers of transition-metal dichalcogenides such as WSe2 have become increasingly attractive due to their potential in electrical and optical applications. Because the properties these 2D systems are known be affected by surroundings, we report how choice substrate material affects monolayer WSe2. To accomplish this study, pump-density-dependent micro-photoluminescence measurements performed with time-integrating time-resolving acquisition techniques. Spectral information power-dependent...
The optical and electronic properties of tungsten disulfide monolayers (WS2) have been extensively studied in the last few years, yet growth techniques for WS2 remain behind other transition metal dichalcogenides (TMDCs) such as MoS2. Here we demonstrate chemical vapor deposition (CVD) continuous monolayer films on mm(2) scales elucidate effects related to hydrogen (H2) gas concentration during growth. crystals were grown by reduction sulfurization WO3 using H2 sulfur evaporated from solid...
Abstract The integration of 2D van der Waals (vdW) magnets with topological insulators or heavy metals holds great potential for realizing next‐generation spintronic memory devices. However, achieving high‐efficiency spin–orbit torque (SOT) switching monolayer vdW at room temperature poses a significant challenge, particularly without an external magnetic field. Here, it is shown field‐free, deterministic, and nonvolatile SOT perpendicular magnetization in the monolayer, diluted...
Abstract Graphene's unique optoelectronic properties are promising to realize photodetectors with ultrafast photoresponse over a wide spectral range from far-infrared ultraviolet radiation. The underlying mechanism of the has been particular focus recent work and was found be either photoelectric or photo-thermoelectric in nature enhanced by hot carrier effects. Graphene supported substrate dominated effect, which is known an order magnitude slower than effect. Here we demonstrate...
We present flexible and stretchable supercapacitors composed of interwoven carbon nanotubes (CNTs) embedded in polydimethylsiloxane (PDMS) substrates. CNTs are grown using atmospheric-pressure chemical vapor deposition (APCVD) on a Si/SiO2 substrate then partially into PDMS. This unique process permits rapid facile integration the CNT–PDMS structure as supercapacitor electrode with high level integrity under various strains. The electrochemical properties measured 30% KOH solution poly(vinyl...
Abstract Flexible energy‐storage devices increasingly attract attention owing to their advantages of providing lightweight, portable, wearable, or implantable capabilities. Many efforts are made explore the structures and fabrication processes flexible for commercialization. Here, most recent advances in based on graphene, graphene oxide (GO), carbon nanotubes (CNTs), described, including supercapacitors batteries. First, properties, synthesis methods, possible applications those...
Two-dimensional materials such as graphene and transition metal dichalcogenides (TMDCs) have received extensive research interest investigations in the past decade. In this research, we used a refined opto-thermal Raman technique to explore thermal transport properties of one popular TMDC material WSe2, single-layer (1L), bilayer (2L), trilayer (3L) forms. This measurement is direct without additional processing material, absorption coefficient WSe2 discovered during process further increase...
Transition metal dichalcogenides (TMDs) are two-dimensional (2D) materials with remarkable electrical, optical, and chemical properties. One promising strategy to tailor the properties of TMDs is create alloys through a dopant-induced modification. Dopants can introduce additional states within bandgap TMDs, leading changes in their electronic, magnetic This paper overviews vapor deposition (CVD) methods dopants into TMD monolayers, discusses advantages, limitations, impacts on structural,...
Hexagonal boron nitride (hBN) is attracting increasing attention for quantum information science due to its ability host carbon-related color centers that perform as robust, high-temperature light sources, well native defects such charged VB– with optically addressable spin states toward spin-based applications. So far, achieving isolation of individual out ensemble emission remains difficult their low yield, warranting the search other candidates. Here, we show oxygen annealing creates...
Magnetic alignment is reported as a facile technique for assembling nanowires into hierarchical structures. Cross junction and T nanowire networks are demonstrated using sequential on unpatterned substrates predefined lithographically patterned ferromagnetic electrodes. The formation of junctions prevails from the first behave electrodes under external magnetic field second alignment. presence prefabricated dominates dipole interactions localized preferential Application cylindrical coaxial...
In this paper, a cell separation technique has been explored using antibody-functionalized Ni nanowires. An antibody (anti-CD31) against mouse endothelial cells (MS1) was conjugated to the nanowire surface through self-assembled monolayers (SAMs) and chemical covalent reactions. The measured cytotoxicity negligible on CD-31 nanowires by tetrazolium salt (MTT) assay. use of functionalized for magnetically separating MS1 revealed that yield closely related concentration nanowire/cell ratio....
Transition metal dichalcogenides (TMDs) have emerged as promising materials to complement graphene for advanced optoelectronics. However, irreversible degradation of chemical vapor deposition-grown monolayer TMDs via oxidation under ambient conditions limits applications TMD-based devices. Here, the growth oxidation-resistant tungsten disulfide (WS2 ) monolayers on is demonstrated, and mechanism WS2 SiO2 , graphene/SiO2 suspended in air elucidated. While a substrate begins within weeks,...
We present a controlled chemical vapor deposition (CVD) growth and transfer of arrayed MoS2 monolayers on predetermined locations. The patterned transition metal oxide (e.g. MoO3) source substrate was contacted face-to-face with an SiO2 substrate, where localized flakes were synthesized both substrates, following CVD procedure. This technique enabled the single crystalline polycrystalline monolayer arrays size location, exclusively locations substrates. As-grown transferred using unique...
This paper describes the results of our development a leak-tight piezoelectric microvalve, operating at extremely high upstream pressures for microspacecraft applications. The device is normally closed microvalve assembled and fabricated primarily from micromachined silicon wafers. consists custom-designed stack actuator bonded onto valve components (such as seat, boss, tether) with entire assembly contained within stainless steel housing. seat configurations include narrow-edge seating...
This paper describes an experimental study on field emission characteristics of individual graphene layers for vacuum nanoelectronics. Graphene were prepared by mechanical exfoliation from a highly oriented pyrolyzed graphite block and placed insulating substrate, with the resulting behavior investigated using nanomanipulator operating inside scanning electron microscope. A pair tungsten tips controlled enabled electric connection without postfabrication. The maximum emitted current was 170...
We fabricated dye sensitized graphene antidot superlattices with the purpose of elucidating role localized edge state density. The fluorescence from deposited molecules was found to strongly quench as a function increasing filling fraction, whereas it enhanced in unpatterned but electrically backgated samples. This contrasting behavior is indicative built-in lateral electric field that accounts for quenching well p-type doping. These findings are great interest light-harvesting applications...
We performed optical annealing experiments at the edges of nanopatterned graphene to study resultant edge reconstruction. The lithographic patterning direction was orthogonal a zigzag edge. μ-Raman spectroscopy shows an increase in polarization contrast G band as function time. Furthermore, transport measurements reveal 50% GNR energy gap after exposure, consistent with increased percentage armchair segments. These results suggest that chirality devices can be optically purified post...
Two-Dimensional transition metal dichalcogenides have been the subject of extensive attention thanks to their unique properties and atomically thin structure. Because its unprecedented room-temperature magnetic properties, iron-doped MoS2 (Fe:MoS2) is considered next-generation quantum material. It essential understand Fe:MoS2's thermal behavior since temperature load/activation are crucial for current nano devices severely limited by management. In this work, Fe:MoS2 synthesized doping Fe...