A5053524324- Semiconductor materials and devices
- Advancements in Semiconductor Devices and Circuit Design
- Graphene research and applications
- 2D Materials and Applications
- Semiconductor materials and interfaces
- Solidification and crystal growth phenomena
- Chalcogenide Semiconductor Thin Films
- Silicon Nanostructures and Photoluminescence
- Nanowire Synthesis and Applications
- Ferroelectric and Negative Capacitance Devices
- Advanced Memory and Neural Computing
- Quantum Dots Synthesis And Properties
- Thin-Film Transistor Technologies
- Metallic Glasses and Amorphous Alloys
- Silicon and Solar Cell Technologies
- Metallurgical Processes and Thermodynamics
- Electronic and Structural Properties of Oxides
- Diamond and Carbon-based Materials Research
- Integrated Circuits and Semiconductor Failure Analysis
- MXene and MAX Phase Materials
- Surface and Thin Film Phenomena
- Molecular Junctions and Nanostructures
- Quantum and electron transport phenomena
- Aluminum Alloy Microstructure Properties
- Electron and X-Ray Spectroscopy Techniques
The University of Tokyo
2016-2025
Osaka University
2014-2021
Indian Institute of Science Education and Research, Tirupati
2021
Kwansei Gakuin University
2021
National Institute for Materials Science
2021
Spintronics Research Network of Japan
2021
Japan Science and Technology Agency
2009-2018
Centre for Research in Engineering Surface Technology
2009-2014
University of Notre Dame
2014
Nanjing University
2014
Synthetic two-dimensional polymers, or bottom-up nanosheets, are ultrathin polymeric frameworks with in-plane periodicity. They can be synthesized in a direct, fashion using atomic, ionic, molecular components. However, few based on carbon-carbon bond formation, which means that there is potential new field of investigation into these fundamentally important chemical bonds. Here, we describe the synthesis all-carbon, π-conjugated graphdiyne nanosheets. A liquid/liquid interfacial protocol...
The contact properties between metal and graphene were examined. electrical measurement on a multiprobe device with different areas revealed that the current flow preferentially entered at edge of metal. analysis using cross-bridge Kelvin structure (CBK) suggested transition from conduction to area occurred for length shorter than transfer ~1 micron. resistivity Ni was measured as ~5*10-6 Ohmcm2 CBK. A simple calculation suggests less 10-9 is required miniaturized field effect transistors.
Hexagonal boron nitride (BN) is widely used as a substrate and gate insulator for two-dimensional (2D) electronic devices. The studies on insulating properties electrical reliability of BN itself, however, are quite limited. Here, we report systematic investigation the dielectric breakdown characteristics using conductive atomic force microscopy. electric field strength was found to be ∼12 MV/cm, which comparable that conventional SiO2 oxides because covalent bonding nature BN. After hard...
2D van der Waals ferroelectric semiconductors have emerged as an attractive building block with immense potential to provide multifunctionality in nanoelectronics. Although several accomplishments been reported resistive switching for out-of-plane ferroelectrics down the monolayer, a purely in-plane has not experimentally validated at monolayer thickness. Herein, micrometer-size SnS is grown on mica by physical vapor deposition, and demonstrated two-terminal device room temperature (RT)....
The mobility of graphene transferred on a SiO2/Si substrate is limited to ∼10 000 cm2V−1s−1. Without understanding the graphene/SiO2 interaction, it difficult improve electrical transport properties. Although surface structures SiO2 such as silanol and siloxane groups are recognized, relation between treatment characteristics has not yet been elucidated. This paper discusses properties specific prepared by O2-plasma treatments reoxidization.
The key to achieve high-quality van der Waals heterostructure devices made of stacking various two-dimensional (2D) layered materials lies in the clean interface without bubbles and wrinkles. Although polymethylmethacrylate (PMMA) is generally used as a sacrificial transfer film due its strong adhesion property, it always dissolved solvent after transfer, resulting unavoidable PMMA residue on top surface. This makes difficult locate areas. In this work, we present fully dry graphene onto...
High-κ dielectrics on Ge have recently attracted much attention as a potential candidate to replace planar silicon transistors for sub-32-nm generations. However, the instability of high-κ/Ge interface, especially desorption germanium monoxide (GeO), hampers development Ge-based devices. Therefore, typical GeO2/Ge structure was chosen investigate GeO desorption. In this contribution, we describe kinetics GeO, including Ge/GeO2 interface reaction, diffusion process during desorption,...
Graphene with a high carrier mobility of more than 10,000 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /Vs on SiO <sub xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> has attracted much attention as promising candidate future high-speed transistor materials. The contact resistance (RC) between graphene and metal electrodes is crucially important for achieving potentially performance from both physics practical viewpoints. This...
We propose a two-step oxidation with high-pressure and low-temperature oxygen annealing to form ideal Ge/GeO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> stacks based on thermodynamic kinetic control. The capacitance-voltage (C-V) characteristics of MISCAPs revealed significant improvements electrical properties, the interface states density (Dit) estimated conductance method that was below 10 <sup...
Graphdiyne (GDY) comprises an important class in functional covalent organic nanosheets based on carbon–carbon bond formation, and recent focus has collected the expansion of its variations. Here we report synthesis a GDY analogue, TP-GDY, which triphenylene as aromatic core. Our liquid/liquid interfacial for (J. Am. Chem. Soc. 2017, 139, 3145) was modified hexaethynyltriphenylene monomer to afford TP-GDY film with free-standing morphology, smooth texture, domain size >1 mm, thickness 220...
Substitutional doping in transition-metal dichalcogenides (TMDCs) is a pivotal strategy for tuning their electronic and optical properties, enabling integration into next-generation optoelectronic devices. This study examines the critical levels at which doped TMDCs transition from nondegenerate to degenerate semiconductors, comparing three-dimensional (3D) bulk with two-dimensional (2D) counterparts. Through systematic characterization of Nb-doped WSe2, we demonstrate that, although high...
The electric properties of mono- and multi-layer graphene films were systematically studied. current modulation increased monotonically with a decrease in the layer number due to reduction interlayer scattering. carrier mobility monolayer was greater than that multilayer linear dispersion relation. On other hand, monolayer, transport significantly sensitive charged impurity density screening effect, which caused larger variation. is thus key for high mobility.
High-pressure oxidation (HPO) of germanium (Ge) for improving electrical properties Ge/GeO2 stacks was investigated. The capacitance–voltage (C–V) characteristics metal/GeO2/Ge capacitors fabricated with HPO revealed improved without any post-deposition annealing, and the interface states density (Dit) reduced to 2×1011 eV-1 cm-2 near midgap. Moreover, refractive index thermally oxidized GeO2 increased by HPO. It is also discussed from a thermodynamic viewpoint system that GeO desorption...
The intrinsic channel properties of monolayer and multilayer graphene were systematically investigated as a function layer number by the exclusion contact resistance using four-probe measurements. We show that continuous change in normalized sheet resistivity from graphite to bilayer is governed one unique property, i.e., band overlap, which markedly increases 1 meV for 11 eight layers eventually reaches 40 graphite. graphene, however, showed deviation temperature dependence due peculiar...
Dielectric breakdown has historically been of great interest from the perspectives fundamental physics and electrical reliability. However, to date, anisotropy in dielectric not discussed. Here, we report an anisotropic strength (EBD) for h-BN, which is used as ideal substrate two-dimensional (2D) material devices. Under a well-controlled relative humidity, EBD values directions both normal parallel c axis (EBD⊥c EBD∥c) were measured be 3 12 MV/cm, respectively. When crystal structure...
Recently, research on transition metal dichalcogenides (TMDCs) has been accelerated by the development of large-scale synthesis based chemical vapor deposition (CVD). However, in most cases, CVD-grown TMDC sheets are composed randomly oriented grains, and thus contain many distorted grain boundaries (GBs) which deteriorate physical properties TMDC. Here, we demonstrate epitaxial growth monolayer tungsten disulfide (WS2) sapphire introducing a high concentration hydrogen during CVD process....
The shift-current photovoltaics of group-IV monochalcogenides has been predicted to be comparable those state-of-the-art Si-based solar cells. However, its exploration prevented from the centrosymmetric layer stacking in thermodynamically stable bulk crystal. Herein, non-centrosymmetric tin sulfide (SnS) is stabilized bottom regions SnS crystals grown on a van der Waals substrate by physical vapor deposition and shift current SnS, combining polarization angle dependence circular...
For the complementary operation of two-dimensional (2D) material-based field-effect transistors (FETs), high-performance p-type FETs are essential. In this study, we applied surface charge-transfer doping from WOx, which has a large work function ∼6.5 eV, selectively to access region WS2 and WSe2 by covering channel with h-BN. By reducing Schottky barrier width at contact injecting holes into valence band, conversion intrinsically n-type trilayer FET was successfully achieved. However, did...
Achieving the direct growth of an ultrathin gate insulator with high uniformity and quality on monolayer transition metal dichalcogenides (TMDCs) remains a challenge due to chemically inert surface TMDCs. Although main solution for this is utilizing buffer layers before oxide deposited atomic layer, method drastically degrades total capacitance stack. In work, we constructed novel high-κ Er2 O3 deposition system based thermal evaporation in differential-pressure-type chamber. A uniform layer...
We have systematically investigated Ge interface passivation methods, and the highest electron (1920 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /Vs) hole mobility (725 been demonstrated by dramatic reduction of D <sub xmlns:xlink="http://www.w3.org/1999/xlink">it</sub> through collaboration self-passivation valency passivation. In Si passivation, it is found that contributes to upper half (worse) lower one (better) in bandgap...
Graphene has attracted much attention as one of promising candidates future high-speed transistor materials because its high carrier mobility more than 10,000 cm2 V-1 s-1. Up to this point, we have focused on the contact properties performance killers, a very small density states in graphene might suppress current injection from metal graphene. This paper systematically reviews metal/graphene and discusses present status requirements specific resistivity.