Directory of Researchers
| ONO Tomoya |  |
| Graduate School of Engineering / Department of Electrical and Electronic Engineering | |
| Professor | |
| Physics |
Researcher Profile and Settings
Affiliation
＜Faculty / Graduate School / Others＞
Graduate School of Engineering / Department of Electrical and Electronic Engineering＜Related Faculty / Graduate School / Others＞
Faculty of Engineering / Department of Electrical and Electronic Engineering
Teaching
- Faculty of Engineering / Department of Electrical and Electronic Engineering, 2022, Engineering Course of Mathematical Physics A
- Faculty of Engineering / Department of Electrical and Electronic Engineering, 2022, Statistical Physics
- Faculty of Engineering / Department of Electrical and Electronic Engineering, 2022, Engineering Course of Mathematical Physics B
- Faculty of Engineering / Department of Electrical and Electronic Engineering, 2022, Semiconductor Electronics ⅡA
- Faculty of Engineering / Department of Electrical and Electronic Engineering, 2022, Semiconductor Device Engineering
- Faculty of Engineering / Department of Electrical and Electronic Engineering, 2022, Semiconductor Electronics ⅡB
- Graduate School of Engineering / Department of Electrical and Electronic Engineering, 2022, Advanced Course on Quantum Mechanics
- Graduate School of Engineering / Department of Electrical and Electronic Engineering, 2022, Structure of Surfaces
Research Activities
Research Interests
Research Areas
- Nanotechnology/Materials / Composite materials and interfaces
- Nanotechnology/Materials / Thin-film surfaces and interfaces
- Natural sciences / Mathematical physics and basic theory
- Natural sciences / Semiconductors, optical and atomic physics
Awards
Jul. 2014 Osaka University, Presidential Awards for Encouragement
Others
Mar. 2011 The Physical Society of Japan, Award for the Encouragement of Young Physicists
Japan society
Jan. 2006 Alexander von Humboldt Research Fellowship
Published Papers
We propose the atomic structures of the 4H-SiC/[Formula: see text] interface for [Formula: see text] face (1[Formula: see text]00), [Formula: see text] face (11[Formula: see text]0), the C face (000[Formula: see text]), and Si face (0001) after NO annealing using the OH-terminated SiC surface models. Our proposed structures preferentially form at the topmost layers of the SiC side of the interface, which agrees with the experimental finding of secondary-ion mass spectrometry; that is, the N atoms accumulate at the interface. In addition, the areal N-atom density is of the order of [Formula: see text] for each plane, which is also consistent with the experimental result. Moreover, the electronic structure on the interface after NO annealing in which the CO bonds are removed and the nitride layer only at the interface is inserted, is free from gap states, although some interface models before NO annealing include the gap states arising from the CO bonds near the valence band edge of the bandgap. Our results imply that NO annealing can contribute to the reduction in the density of interface defects by forming the nitride layer.
Corresponding, AIP Publishing, 21 Oct. 2022, Journal of Applied Physics, 132 (15), 155701 - 155701[Refereed]
Scientific journal
Single-molecule measurements of biomaterials bring novel insights into cellular events. For almost all of these events, post-translational modifications (PTMs), which alter the properties of proteins through their chemical modifications, constitute essential regulatory mechanisms. However, suitable single-molecule methodology to study PTMs is very limited. Here we show single-molecule detection of peptide phosphorylation, an archetypal PTM, based on electrical measurements. We found that the phosphate group stably bridges a nanogap between metal electrodes and exhibited high electrical conductance, which enables specific single-molecule detection of peptide phosphorylation. The present methodology paves the way to single-molecule studies of PTMs, such as single-molecule kinetics for enzymatic modification of proteins as shown here.
28 Sep. 2022, Journal of the American Chemical Society, 144 (38), 17449 - 17456, English, International magazine[Refereed]
Scientific journal
Graphene on [Formula: see text]-FePd(001), which has been experimentally studied in recent years, is a heterogeneous interface with a significant lattice symmetry mismatch between the honeycomb structure of graphene and tetragonal alloy surface. In this work, we report on the density functional study of its atomic-scale configurations, electronic and magnetic properties, and adsorption mechanism, which have not been well understood in previous experimental studies. We propose various atomic-scale models, including simple nontwisted and low-strain twisted interfaces, and analyze their energetical stability by performing structural optimizations using the van der Waals interactions of both DFT-D2 and optB86b-vdW functionals. The binding energy of the most stable structure reached [Formula: see text] eV/atom for DFT-D2 ([Formula: see text] eV/atom for optB86b-vdW). The calculated FePd-graphene spacing distance was approximately 2 Å, which successfully reproduced the experimental value. We also find out characteristic behaviors: the modulation of [Formula: see text]-bands, the suppression of the site-dependence of adsorption energy, and the rise of moiré-like corrugated buckling. In addition, our atomic structure is expected to help build low-cost computational models for investigating the physical properties of [Formula: see text] alloys/two-dimensional interfaces.
AIP Publishing, 07 Sep. 2022, Journal of Applied Physics, 132 (9), 095301 - 095301[Refereed]
Scientific journal
Abstract The stability and formation mechanism of the defects relevant to silicon and carbon vacancies at the 4H-SiC($000\bar{1}$)/SiO2 interface after wet oxidation are investigated by first-principles calculation based on the density functional theory. The difference in the total energy of the defects agrees with the experimental results concerning the density of defects. We found that the characteristic behaviors of the generation of defects are explained by the positions of vacancies and antisites in the SiC($000\bar{1}$) substrate and that the formation of silicon and carbon vacancies is relevant to the generation mechanism of defects. The generation of silicon and carbon vacancies is attributed to the termination of dangling bonds by H atoms introduced by wet oxidation, resulting in the generation of carbon-antisite–carbon-vacancy and divacancies defects in wet oxidation.
Corresponding, IOP Publishing, 01 Jul. 2022, Japanese Journal of Applied Physics, 61 (SH), SH1001 - SH1001[Refereed]
Scientific journal
- Last, Dec. 2021, Journal of Physical Society of Japan, 90 (12), 124713, EnglishFirst-Principles Study on Structure and Anisotropy of High N-atom Density Layer in 4H-SiC
[Refereed]
Scientific journal
- American Physical Society (APS), 14 Jan. 2021, Physical Review Research, 3 (1), 013038, English
[Refereed]
Scientific journal
Abstract Using first-principles calculations, we investigate the possibility of realizing valley Hall effects (VHE) in blistered graphene sheets. We show that the Van Hove singularities (VHS) induced by structural deformations can give rise to interesting spin–valley Hall phenomena. The broken degeneracy of spin degree of freedom results in spin-filtered VH states and the valley conductivity have a Hall plateau of ±e2/2h , while the blistered structures with time-reversal symmetry show the VHE with the opposite sign of$$\sigma _{xy}^{K/K^{\prime } }$$ h ) in the two valleys. Remarkably, these results show that the distinguishable chiral valley pseudospin state can occur even in the presence of VHS induced spin splitting. The robust chiral spin–momentum textures in both massless and massive Dirac cones of the blistered systems indicate significant suppression of carrier back-scattering. Our study provides a different approach to realize spin-filtered and spin-valley contrasting Hall effects in graphene-based devices without any external field.Springer Science and Business Media LLC, Dec. 2020, npj Computational Materials, 6 (1), English[Refereed]
Scientific journal
Abstract In contrast to the current research on two-dimensional (2D) materials, which is mainly focused on graphene and transition metal dichalcogenide-like structures, studies on 2D transition metal oxides are rare. By using ab initio calculations along with Monte Carlo simulations and nonequilibrium Green’s function method, we demonstrate that the transition metal oxide monolayer (ML) of Cr2O3 is an ideal candidate for next-generation spintronics applications. 2D Cr2O3 has honeycomb-kagome lattice, where the Dirac and strongly correlated fermions coexist around the Fermi level. Furthermore, the spin exchange coupling constant shows strong ferromagnetic (FM) interaction between Cr atoms. Cr2O3 ML has a robust half-metallic behavior with a large spin gap of ~3.9 eV and adequate Curie temperature. Interestingly, an intrinsic Ising FM characteristic is observed with a giant perpendicular magnetocrystalline anisotropy energy of ~0.9 meV. Most remarkably, nonequilibrium Green’s function calculations reveal that the Cr2O3 ML exhibits an excellent spin filtering effect.Last, Springer Science and Business Media LLC, Dec. 2020, npj 2D Materials and Applications, 4 (1), 39 - 39, English[Refereed]
Scientific journal
- Last, Physical Society of Japan, 15 Mar. 2020, Journal of the Physical Society of Japan, 89 (3), 034708 - 034708, English
[Refereed]
Scientific journal
- Aug. 2019, Physical Review B, 100 (07), 075413, English
[Refereed]
Scientific journal
- Jul. 2019, Materials Science Forum, 963, 208 - 212, English
[Refereed]
Scientific journal
- May 2019, Angewandte Chemie International Edition, 58, 9109 - 9113, English
[Refereed]
Scientific journal
- Nov. 2018, Physical Review B, 98 (19), 195442, English
[Refereed]
Scientific journal
- Institute of Physics, Jun. 2018, Jpn. J. Appl. Phys., 57 (6), 66501, English
[Refereed]
Scientific journal
- AMER PHYSICAL SOC, May 2018, PHYSICAL REVIEW B, 97 (19), 195449, English
[Refereed]
Scientific journal
- AMER PHYSICAL SOC, Mar. 2018, PHYSICAL REVIEW B, 97 (11), 115450, English
[Refereed]
Scientific journal
- The Physical Society of Japan, 2018, Meeting Abstracts of the Physical Society of Japan, 73, 2680 - 2680, Japanese
Scientific journal
In a metal/molecule hybrid system, unavoidable electrical mismatch exists between metal continuum states and frontier molecular orbitals. This causes energy loss in the electron conduction across the metal/molecule interface. For efficient use of energy in a metal/molecule hybrid system, it is necessary to control interfacial electronic structures. Here we demonstrate that electrical matching between a gold substrate and π-conjugated molecular wires can be obtained by using monatomic foreign metal interlayers, which can change the degree of d-π* back-donation at metal/anchor contacts. This interfacial control leads to energy level alignment between the Fermi level of the metal electrode and conduction molecular orbitals, resulting in resonant electron conduction in the metal/molecule hybrid system. When this method is applied to molecule-modified electrocatalysts, the heterogeneous electrochemical reaction rate is considerably improved with significant suppression of energy loss at the internal electron conduction.
AMER CHEMICAL SOC, Jan. 2018, ACS nano, 12 (2), 1228 - 1235, English[Refereed]
Scientific journal
- Nov. 2017, Proc. of The International Conference for High Performance Computing, Networking, Storage and Analysis (SC'17), EnglishEfficient and Scalable Calculation of Complex Band Structure using Sakurai-Sugiura Method
[Refereed]
International conference proceedings
Density functional theory calculations are carried out to investigate the atomic and electronic structures of the 4H-SiC(0001)/SiO2 interface. We find two characteristic interface atomic structures in scanning transmission electron microscopy images: One is an interface in which the density of atoms at the first interfacial SiC bilayer is greater than that in the SiC substrate, while the other is an interface where the density of atoms at the first interfacial SiC bilayer is lower. Density functional theory calculations reveal that the difference in the scanning transmission electron microscopy images is a reflection of the atomic structures of these two interfaces. In addition, it has been reported that the floating states, which appear at the conduction band edge of a 4H-SiC(0001)/SiO2 interface, affect the electronic structure of the interface and cause marked scattering of the electrons flowing along the interface [S. Iwase, C. J. Kirkham, and T. Ono, Phys. Rev. B 95, 041302(R) (2017)]. Interestingly, we find that the floating states do not appear at the conduction band edge of one of the two interfaces. These results provide physical insights into understanding and controlling the electronic structure and carrier mobility of electronic devices using wide-band-gap semiconductors.
AMER PHYSICAL SOC, Sep. 2017, PHYSICAL REVIEW B, 96 (11), 115311 - 115311, English[Refereed]
Scientific journal
The self-energy term used in transport calculations, which describes the coupling between electrode and transition regions, is able to be evaluated only from a limited number of the propagating and evanescent waves of a bulk electrode. This obviously contributes toward the reduction of the computational expenses in transport calculations. In this paper, we present a mathematical formula for reducing the computational expenses further without using any approximation and without losing accuracy. So far, the self-energy term has been handled as a matrix with the same dimension as the Hamiltonian submatrix representing the interaction between an electrode and a transition region. In this work, through the singular-value decomposition of the submatrix, the self-energy matrix is handled as a smaller matrix, whose dimension is the rank number of the Hamiltonian submatrix. This procedure is practical in the case of using the pseudopotentials in a separable form, and the computational expenses for determining the self-energy matrix are reduced by 90% when employing a code based on the real-space finite-difference formalism and projector-augmented wave method. In addition, this technique is
AMER PHYSICAL SOC, Mar. 2017, Physical review. E, 95 (3), 033309 - 33309, English[Refereed]
Scientific journal
- Feb. 2017, Quantum Matter, 6 (1), 4 - 17, English
[Refereed]
Research society
We introduce a first-principles study to clarify the carrier-scattering property at the SiC/SiO2. Interestingly, the electron transport at the conduction-band edge is significantly affected by the introduction of oxygen, even though there are no electrically active defects. The origin of the large scattering is explained by the behavior of the internal-space states (ISSs). Moreover, the effect of the ISSs is larger than that of the electrically active carbon-related defects. This result indicates that an additional scattering not considered in a conventional Si/SiO2 occurs at the SiC/SiO2.
AMER PHYSICAL SOC, Jan. 2017, PHYSICAL REVIEW B, 95 (4), 041302 - 41302, English[Refereed]
Scientific journal
- Oct. 2016, ECS Transactions, 75 (5), 121 - 126, English
[Refereed]
Scientific journal
We review a series of first-principles studies on the defect generation mechanism and electronic structures of the Ge/GeO<inf>2</inf>interface. Several experimental and theoretical studies proved that Si atoms at the Si/SiO<inf>2</inf>interface are emitted to release interface stress. In contrast, total-energy calculation reveals that Ge atoms at the Ge/GeO<inf>2</inf>interface are hardly emitted, resulting in the low trap density. Even if defects are generated, those at the Ge/GeO<inf>2</inf>interface are found to behave differently from those at the Si/SiO<inf>2</inf>interface. The states attributed to the dangling bonds at the Ge/GeO<inf>2</inf>interface lie below the valence-band maximum of Ge, while those at the Si/SiO<inf>2</inf>interface generate the defect state within the band gap of Si. First-principles electron-transport calculation elucidates that this characteristic behavior of the defect states is relevant to the difference in the leakage current through the Si/SiO<inf>2</inf>and Ge/GeO<inf>2</inf>interfaces.
The Japan Society of Applied Physics, Jul. 2016, Jpn. J. Appl. Phys., 55 (8), 08PA01, Japanese[Refereed]
Research society
第一原理電気伝導特性計算法は, デバイス中の電子移動を解析・予測する手段として開発されてきたが, 従来の電子状態計算よりも非常に計算コストが高く, 実デバイスの機能予測を行うことは困難であった. 近年の超並列計算機の飛躍的な性能向上により, 計算コストの課題を超並列計算に適した実空間差分法に基づく数値計算法で回避できることが示され, 第一原理計算を利用した新機能・新原理デバイスのデザインへの道が開かれた. 今後, 超並列計算機を駆使して, 大規模シミュレーションによるデバイスデザインを実現するには, ボトルネックの計算コストのオーダーを下げる必要がある. 本稿では, 実空間差分法を用いた第一原理電気伝導特性計算のいくつかのボトルネック部分を, オーダーN 化によって高速化する取り組みについて紹介する.
分子シミュレーション研究会, Apr. 2016, アンサンブル, 18 (2), 82 - 89, Japanese[Refereed]
Research society
- Apr. 2016, Materials Science Forum, 858, 457 - 460, English
[Refereed]
Scientific journal
We investigate the effect of SiC stacking and interfacial O defects on the electronic structure of the 4H-SiC/SiO2 interface via first-principles calculations. We find interlayer states along the SiC conduction band edge, whose location changes depending on which of two possible lattice sites, h or k, is at the interface. Excess O atoms at the interface lead to defect structures which alter the electronic structure. Changes to the valence band edge are the same whether h or k sites are at the interface. On the other hand, defects remove the interlayer state of the conduction band edge between the first and second SiC bilayers if an h site is at the interface, but have no effect when there is a k site. The variation of the conduction band edge at the interface is interpreted in terms of floating states, a particular property of SiC.
The Physical Society of Japan, Mar. 2016, JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN, 85 (2), 024701 - 1-5, English[Refereed]
Scientific journal
- The Physical Society of Japan (JPS), 2016, Meeting Abstracts of the Physical Society of Japan, 71, 2649 - 2649, Japanese
近年、従来のSiO_2ゲート絶縁膜を用いたトランジスタの薄膜化限界に伴い、高誘電(High-k)材料を用いたトランジスタが注目を集めている。先行研究としてはSiO_2中間層形成の発見、3層界面での安定構造の探索、及び酸素空孔欠陥位置の特定等が行われている。我々のグループでは、3層界面における酸素空孔欠陥がもたらすリーク電流、すなわちデバイスの性能低下に関するシュミレーションを行った。
The Physical Society of Japan, 2016, Meeting Abstracts of the Physical Society of Japan, 71, 2337 - 2337, Japanese大規模なナノ構造体の電子輸送特性を調べるためには、高精度かつ高速な第一原理伝導計算手法の開発が必要である。本研究では、電極の自己エネルギー項が一般化ブロッホ波の射影演算子として定義できることを利用した新たな伝導計算手法の開発を行った。発表では、新たに開発した方法・アルゴリズムおよび本手法を用いた数値計算例について紹介する。
The Physical Society of Japan, 2016, Meeting Abstracts of the Physical Society of Japan, 71, 2899 - 2899, JapaneseWe present a fast and stable numerical technique to obtain the self-energy terms of electrodes for first-principles electron transport calculations. Although first-principles calculations based on the real-space finite-difference method are advantageous for execution on massively parallel computers, large-scale transport calculations are hampered by the computational cost and numerical instability of the computation of the self-energy terms. Using the orthogonal complement vectors of the space spanned by the generalized Bloch waves that actually contribute to transport phenomena, the computational accuracy of transport properties is significantly improved with a moderate computational cost. To demonstrate the efficiency of the present technique, the electron transport properties of a Stone-Wales (SW) defect in graphene and silicene are examined. The resonance scattering of the SW defect is observed in the conductance spectrum of silicene since the σ∗ state of silicene lies near the Fermi energy. In addition, we found that one conduction channel is sensitive to a defect near the Fermi energy, while the other channel is hardly affected. This characteristic behavior of the conduction channels is interpreted in terms of the bonding network between the bilattices of the honeycomb structure in the formation of the SW defect. The present technique enables us to distinguish the different behaviors of the two conduction channels in graphene and silicene owing to its excellent accuracy.
AMER PHYSICAL SOC, Jan. 2016, PHYSICAL REVIEW B, 93 (4), 045421 - 45421, English[Refereed]
Scientific journal
- Oct. 2015, Quantum Matter, 45 (5), 403 - 415, English
[Refereed]
Research society
We develop a first-principles electron-transport simulator based on the Lippmann-Schwinger (LS) equation within the framework of the real-space finite-difference scheme. In our fully real-space-based LS (grid LS) method, the ratio expression technique for the scattering wave functions and the Green's function elements of the reference system is employed to avoid numerical collapse. Furthermore, we present analytical expressions and/or prominent calculation procedures for the retarded Green's function, which are utilized in the grid LS approach. In order to demonstrate the performance of the grid LS method, we simulate the electron-transport properties of the semiconductor-oxide interfaces sandwiched between semi-infinite jellium electrodes. The results confirm that the leakage current through the (001)Si−SiO2 model becomes much larger when the dangling-bond state is induced by a defect in the oxygen layer, while that through the (001)Ge−GeO2 model is insensitive to the dangling bond state.
AMER PHYSICAL SOC, Sep. 2015, PHYSICAL REVIEW E, 92 (3), 033301 - 33301, English[Refereed]
Scientific journal
We propose an efficient procedure to obtain Green's functions by combining the shifted conjugate orthogonal conjugate gradient (shifted COCG) method with the nonequilibrium Green's function (NEGF) method based on a real-space finite-difference (RSFD) approach. The bottleneck of the computation in the NEGF scheme is matrix inversion of the Hamiltonian including the self-energy terms of electrodes to obtain the perturbed Green's function in the transition region. This procedure first computes unperturbed Green's functions and calculates perturbed Green's functions from the unperturbed ones using a mathematically strict relation. Since the matrices to be inverted to obtain the unperturbed Green's functions are sparse, complex-symmetric, and shifted for a given set of sampling energy points, we can use the shifted COCG method, in which once the Green's function for a reference energy point has been calculated the Green's functions for the other energy points can be obtained with a moderate computational cost. We calculate the transport properties of a C-60@(10,10) carbon nanotube (CNT) peapod suspended by (10,10)CNTs as an example of a large-scale transport calculation. The proposed sc
AMER PHYSICAL SOC, Jun. 2015, PHYSICAL REVIEW E, 91 (6), 063305 - 63305, English[Refereed]
Scientific journal
We investigate the electron-transport properties of ethyne-bridged diphenyl zinc-porphyrin molecules suspended between gold (111) electrodes by first-principles calculations within the framework of density functional theory. It is found that the conductance of a molecular junction in which phenyl and porphyrin rings are perpendicular is reduced by three orders of magnitude compared with that of a junction in which the phenyl and porphyrin rings are coplanar. In the coplanar configuration, electrons are transmitted through p states, which extend over the whole molecule. In the perpendicular configuration, the conductance is suppressed because of the reduction of electron hopping between p states of the phenyl ring and s states of the porphyrin ring. (C) 2015 The Japan Society of Applied Physics
JAPAN SOC APPLIED PHYSICS, May 2015, JAPANESE JOURNAL OF APPLIED PHYSICS, 54 (5), 055201 - 55201, English[Refereed]
Scientific journal
- Japan Society for Simmulation Technology, Mar. 2015, Journal of the Japan Society for Simulation Technology, 34 (1), 18 - 22, JapaneseFirst-principles Study on Transport Property of Nanostructures Using Real-space Finite-difference Method(
Current Situation and Future Aspect on Nano-technology Simulation) [Refereed]
Research society
The effect of SiO2 layers during the thermal oxidation of a 4H-SiC(0001) substrate is examined by performing the first-principles total-energy calculations. Although it is expected that a CO molecule is the most preferable product during the oxidation, CO2 molecules are mainly emitted from the SiC surface at the initial stage of the oxidation. As the oxidation proceeds, CO2 emission becomes less favorable and CO molecules are emitted from the interface. We conclude that the interface stress due to the lattice constant mismatch between 4H-SiC(0001) and SiO2 is responsible for the removal of C during the oxidation, resulting in the characteristic electronic property of the interface fabricated by the thermal oxidation.
AMER INST PHYSICS, Feb. 2015, APPLIED PHYSICS LETTERS, 106 (8), 081601 - 81601, English[Refereed]
Scientific journal
We investigate the electronic structures of graphene with an adsorbed Fe, Co, or Ni adatom in the presence of spin–orbit coupling by density functional theory calculations. As a result of spin–orbit coupling, energy gaps are opened at the crossing points of spin-up and spin-down bands near the Dirac point in the cases of Fe and Co adatoms. In the case of the Ni adatom, the Rashba effect is observed with a
The Physical Society of Japan (JPS), Aug. 2014, Journal of the Physical Society of Japan, 83 (9), 094716 - 1-4, Japanesek -dependent energy shift of the π bands at the bottom of the Fermi surface. The calculated magnetic anisotropy energies reveal that the Fe adatom exhibits an in-plane easy magnetization axis, while the Co adatom exhibits an out-of-plane easy axis.[Refereed]
Scientific journal
In density functional theory, solutions of the Kohn--Sham equation correspond to stationary states of the energy functional. Most calculations converge to a minima of that functional, but in complex noncollinear magnetic systems the energy landscape shows many saddle points (or saddle-like points where the first variation of the energy functional is small) and it depends on the density mixing algorithm which stationary state is reached. This causes a convergence problem that frequently arises when the widely used Broyden algorithm is used to search the energy minima of noncollinear magnetic systems. Calculations of Fe and Mn systems illustrate how a small modification of the mixing algorithm allows to overcome this difficulty and to relax the magnetic moments' rotational degrees of freedom efficiently.
The Physical Society of Japan (JPS), Nov. 2013, Journal of the Physical Society of Japan, 82 (11), 114706 - 114706-10, English[Refereed]
Scientific journal
- Oct. 2013, AIP Conference Proceedings, 1558, 1524 - 1527, English
[Refereed]
Scientific journal
- Oct. 2013, The Journal of Physical Chemistry C, 117 (46), 24115 - 24120, English
[Refereed]
Scientific journal
- SPRINGER, May 2013, NANOSCALE RESEARCH LETTERS, 8, 199, English
[Refereed]
Scientific journal
- AMER PHYSICAL SOC, Feb. 2013, PHYSICAL REVIEW B, 87 (8), 085311, English
[Refereed]
Scientific journal
Germanium (Ge)-based high-mobility metal-oxide-semiconductor field-effect transistors (MOSFETs) have gained considerable attention because they perform better than common Si-based devices. Although degraded electrical property of germanium oxide (GeO2) gate insulators is considered the most serious obstacle for implementing Ge-channel for future MOSFETs, remarkable progress has been made recently. This article overviews both fundamental and technological aspects of thermally grown GeO2, and discusses strategies for achieving ultrathin gate insulators for high-performance Ge-based MOSFETs. Our experimental and theoretical studies revealed that, despite excellent electrical property of GeO2/Ge interface, its poor stability is a big concern, especially for ultrathin dielectrics. To overcome this problem, we investigated the impact of plasma nitridation of Ge and GeO2 surfaces, in terms of surface cleaning, stability, and electrical properties of the nitrides. On the basis of the experimental findings, we have proposed high-quality Ge oxynitride (GeON) gate dielectrics, which consist of stable nitrogen-rich capping layers on ultrathin oxides. We implemented the GeON gate dielectrics into Ge-channel pMOSFETs and successfully demonstrated hole mobility that was 2.4 times higher than Si universal mobility. (c) 2012 Elsevier B.V. All rights reserved.
ELSEVIER SCIENCE BV, Dec. 2012, CURRENT APPLIED PHYSICS, 12, S10 - S19, English[Refereed]
Scientific journal
- Dec. 2012, Current Applied Physics, 12 (3), S100 - S104, English
[Refereed]
Scientific journal
We demonstrate an efficient nonequilibrium Green's function transport calculation procedure based on the real-space finite-difference method. The direct inversion of matrices for obtaining the self-energy terms of electrodes is computationally demanding in the real-space method because the matrix dimension corresponds to the number of grid points in the unit cell of electrodes, which is much larger than that of sites in the tight-binding approach. The procedure using the ratio matrices of the overbridging boundary-matching technique, which is related to the wave functions of a couple of grid planes in the matching regions, greatly reduces the computational effort to calculate self-energy terms without losing mathematical strictness. In addition, the present procedure saves computational time to obtain the Green's function of the semi-infinite system required in the Landauer-Büttiker formula. Moreover, the compact expression to relate Green's functions and scattering wave functions, which provide a real-space picture of the scattering process, is introduced. An example of the calculated results is given for the transport property of the BN ring connected to (9,0) carbon nanotubes. The wave-function matching at the interface reveals that the rotational symmetry of wave functions with respect to the tube axis plays an important role in electron transport. Since the states coming from and going to electrodes show threefold rotational symmetry, the states in the vicinity of the Fermi level, the wave function of which exhibits fivefold symmetry, do not contribute to the electron transport through the BN ring.
American Physical Society, Jul. 2012, Physical Review B, 86 (19), 195406 - 195406, English[Refereed]
Scientific journal
The magnetic moment and spin-polarized electron transport properties of triangular graphene flakes surrounded by boron nitride sheets (BNC structures) are studied by first-principles calculation based on density functional theory. Their dependence on the BNC structure is discussed, revealing that small graphene flakes surrounded by large BN segments have a large magnetic moment. When the BNC structure is suspended between graphene electrodes, the spin-polarized charge density distribution accumulates at the edge of the graphene flakes and no spin polarization is observed in the graphene electrodes. We also found that the BNC structure exhibits perfectly spin-polarized transport properties in a wide energy window around the Fermi level. Our first-principles results indicate that the BNC structure provides for the new possibilities for the electrical control of spin.
American Physical Society, Dec. 2011, Physical Review B, 84 (22), 224424, English[Refereed]
Scientific journal
- Oct. 2011, Journal of Physics: Condensed Matter, 23 (39), 394202, English
[Refereed]
Scientific journal
- Oct. 2011, Journal of Physics: Condensed Matter, 23 (39), 394203, English
[Refereed]
Scientific journal
- Oct. 2011, Physical Review B, 84 (16), 165410, English
[Refereed]
Scientific journal
- Aug. 2011, Physical Review B, 84 (8), 085319, English
[Refereed]
Scientific journal
- Jul. 2011, Microscopy and Microanalysis, 17 (S2), 488 - 489, English
[Refereed]
Scientific journal
- Jul. 2011, Physical Review B, 84 (3), 035401, English
[Refereed]
Scientific journal
The detailed analysis of the structural variations of three GeO2 and SiO2 polymorphs ($\alpha$-quartz, $\alpha$-cristobalite, and rutile) under compression and expansion pressure is reported. First-principles total-energy calculations reveal that the rutile structure is the most stable phase among the phases of GeO2, while SiO2 preferentially forms quartz. GeO4 tetrahedras of quartz and cristobalite GeO2 phases at the equilibrium volume are more significantly distorted than those of SiO2. Moreover, in the case of quartz GeO2 and cristobalite GeO2, all O--Ge--O bond angles vary when the volume of the GeO2 bulk changes from the equilibrium point, which causes further deformation of tetrahedra. In contrast, the tilt angle formed by Si--O--Si in SiO2 markedly changes. This flexibility of the O--Ge--O bonds reduces the stress at the Ge/GeO2 interface due to the lattice-constant mismatch and results in the low defective interface observed in the experiments [Matsubara et al.: Appl. Phys. Lett. 93 (2008) 032104; Hosoi et al.: Appl. Phys. Lett. 94 (2009) 202112].
The Japan Society of Applied Physics, Feb. 2011, Jpn. J. Appl. Phys., 50 (2), 021503 - 021503-5, English[Refereed]
Scientific journal
The electronic structures of dangling bonds (DBs) at Ge/GeO2 and Si/SiO2 interfaces are explored by first-principles calculations. A comparative study of the DBs shows that the trigonal bonds of Ge around Ge-DBs are sharp, while those of Si around Si-DBs are planar. Moreover, the Ge-DB states do not lie near the midgap between the valence band top and conduction band bottom, while the Si-DB states clearly appear. These features are explained by the metallic properties of the bonding network of the Ge/GeO2 interface and agree with the different characteristics of the electron spin-resonance signals from these interfaces.
The Japan Society of Applied Physics, Jan. 2011, Appl. Phys. Exp., 4 (2), 021303 - 021303-3, English[Refereed]
Scientific journal
- Nov. 2010, Phys. Rev. B, 82 (20), 205115, English
[Refereed]
Scientific journal
We present a time-saving simulator within the framework of the density functional theory to calculate the transport properties of electrons through nanostructures suspended between semi-infinite electrodes. By introducing the Fourier transform and preconditioning conjugate-gradient algorithms into the simulator, a highly efficient performance can be achieved in determining scattering wave functions and electron-transport properties of nanostructures suspended between semi-infinite jellium electrodes. To demonstrate the performance of the present algorithms, we study the conductance of metallic nanowires and the origin of the oscillatory behavior in the conductance of an Ir nanowire. It is confirmed that the s- dz2 channel of the Ir nanowire exhibits the transmission oscillation with a period of two-atom length, which is also dominant in the experimentally obtained conductance trace.
American Physical Society, Nov. 2010, Phys. Rev. E, 82 (5), 056706 - 56706, English[Refereed]
Scientific journal
- Dec. 2009, Journal of Computational and Theoretical Nanoscience, 6 (12), 2624 - 2628, English
[Refereed]
Scientific journal
- Jul. 2009, Applied Physics Letters, 95 (1), 011908, English
[Refereed]
Scientific journal
- May 2009, Phys. Rev. B, 79 (19), 195326, English
[Refereed]
Scientific journal
- Mar. 2009, The Journal of Physical Chemistry C, 113, 6256 - 6260, English
[Refereed]
Scientific journal
- Feb. 2009, Journal of Physics: Condensed Matter, 21 (6), 064240, English
[Refereed]
Scientific journal
- Apr. 2008, Surface Interface Analysis, 40, 1063 - 1066, English
[Refereed]
Scientific journal
- Apr. 2008, Surface Interface Analysis, 40, 1067 - 1070, English
[Refereed]
Scientific journal
- Feb. 2008, Phys. Rev. B, 78 (3), 035426, English
[Refereed]
Scientific journal
- Aug. 2007, Journal of Physics: Condensed Matter, 19 (36), 365201, English
[Refereed]
Scientific journal
- Aug. 2007, Journal of Physics: Condensed Matter, 19 (36), 365202, English
[Refereed]
Scientific journal
- Aug. 2007, Journal of Computational and Theoretical Nanoscience, 4 (5), 840 - 859, English
[Refereed]
Scientific journal
- Aug. 2007, Journal of Physics: Condensed Matter, 19 (36), 365205, English
[Refereed]
Scientific journal
- Mar. 2007, Science and Technology of Advanced Materials, 8 (3), 204 - 207, English
[Refereed]
Scientific journal
- Mar. 2007, Science and Technology of Advanced Materials, 8 (3), 200 - 203, English
[Refereed]
Scientific journal
- Feb. 2007, Science and Technology of Advanced Materials, 8 (3), 196 - 199, English
[Refereed]
Scientific journal
- Jan. 2007, Phys. Rev. Lett., 98 (02), 026804, English
[Refereed]
Scientific journal
- Dec. 2006, Phys. Rev. B, 73 (24), 245314, English
[Refereed]
Scientific journal
- Nov. 2006, Phys. Rev. E, 74 (5), 056704, English
[Refereed]
Scientific journal
- Apr. 2006, Physica B, 376-377, 389 - 391, English
[Refereed]
Scientific journal
- Apr. 2006, Physica B, 376-377, 320 - 323, English
[Refereed]
Scientific journal
We present a first-principles study of the electron conduction properties of single-row gold nanowires suspended between semi-infinite gold crystalline electrodes. It is found that the single-row gold nanowires exhibit the quantized conductance of ${\sim}1G_{0}$ ($G_{0}=2e^{2}/h$). Moreover, the conductance oscillation depending on the number of atoms constituting the nanowires is observed with the occurrence of the bunching of high electron density with two atom-lengths in the channel density distribution.
INSTITUTE OF PURE AND APPLIED PHYSICS, Mar. 2006, Jpn. J. Appl. Phys., 45 (3B), 2132 - 2135, English[Refereed]
Scientific journal
The tunneling current flowing between molecule-adsorbed Si(001) surfaces and a tip in scanning tunneling microscopy (STM) is studied using the first-principles electron-transport calculations. The amount of the tunneling current evaluated in this study is consistent with the experimental results. The tunneling current with the tip above the molecule-adsorbed dimer is lower than that with the tip above the bare dimer, which is interpreted by the stabilization of the Si–Si $\pi$ bonding states due to adsorption of the molecules. These results agree with the experimental results, where molecule-adsorbed dimers look geometrically lower than bare dimers.
INSTITUTE OF PURE AND APPLIED PHYSICS, Mar. 2006, Jpn. J. Appl. Phys., 45(3B), 2154-2157/, (3), 2154 - 2157, English[Refereed]
Scientific journal
- Dec. 2005, Physical Review B, 72 (12), 125318, English
[Refereed]
Scientific journal
- AIP Publishing, Nov. 2005, Journal of Applied Physics, 98 (10), 101325 - 103525, English
[Refereed]
Scientific journal
- Sep. 2005, Physical Review B, 72 (11), 113306, English
[Refereed]
Scientific journal
- Aug. 2005, Physical Review B, 72 (8), 085105, English
[Refereed]
Scientific journal
Cone-shaped diamond-tip field electron emitter arrays (boron-doped synthetic single crystal diamond chip, (100) face, type Ib) were fabricated utilizing the SOG(spin-on glass) mask and oxygen reactive ion beam, and characterized. The tip radius of the fabricated diamond emitter arrays was less than 30nm. The threshold electric field of 7.5V/μm and the work function of 3.36eV were obtained from the diamond-tip field emitter array. The experiments on the field emission of the diamond-tip field emitter array at the applied voltage of 1000V for 400min show that the field emission current increased gradually at 60min. The mechanism of this phenomenon was investigated in atomic level by employing the first-priniples molecular-dynamics simulation method. The simulation results show that the mechanism of the phenomenon was not the movement of atoms of the diamond but the movement of atoms of the hydrocarbon deposited during the field emission.
The Japan Society for Precision Engineering, Aug. 2005, Journal of the Japan Society for Precision Engineering, 71 (8), 1015 - 1020, Japanese[Refereed]
Scientific journal
We develop a method for high-speed and high-accuracy first-principles calculations to derive the ground-state electronic structure by directly minimizing the energy functional. Making efficient use of the advantages of the real-space finite-difference method, we apply arbitrary boundary conditions and employ spatially localized orbitals. These advantages enable us to calculate the ground-state electronic structure of a nanostructure sandwiched between crystalline electrodes. The framework of this method and numerical examples for metallic nanowires are presented.
The Japan Institute of Metals, 20 Jun. 2005, The Journal of the Japan Institute of Metals.A, 69 (6), 457 - 459, Japanese- Feb. 2005, Nanotechnology, English
[Refereed]
Scientific journal
- 日本表面科学会, Feb. 2005, Journal of the Surface Science Society of Japan, 26 (2), 36 - 40, Japanese
[Refereed]
Scientific journal
- Jan. 2005, Physical Review B, 72(8), 085115 1-12/,, English
[Refereed]
Scientific journal
- Jan. 2005, Surface Science, 577, 42-46, (2005), 577, 42-46,/,, English
[Refereed]
Scientific journal
- Nov. 2004, Solid State Physics, 39 (11), 848 - 854, JapaneseFirst-Principles Study on Electron Transport Properties of Nano-scale Structures
[Refereed]
Research society
- Nov. 2004, Nanotechnology, 15 (11), 1882 - 1885, English
[Refereed]
Scientific journal
- Jul. 2004, Physical Review B, 70 (4), 033403, English
[Refereed]
Scientific journal
We present first-principles calculations of electron conduction properties of monatomic sodium wires suspended between semi-infinite crystalline electrodes, using the overbridging boundary-matching method. We find that the conductances oscillate depending on the number of atoms in the wire, Natom. Furthermore, the values of conductances are ∼3 G0 (G0 = 2e2/h) for the closed packed structure and ∼1 G0 for single-row wires, which is in agreement with the experimental results of the conductance histogram.
The Japan Institute of Metals and Materials, May 2004, Materials Transactions, 45 (5), 1419 - 1421, English[Refereed]
Scientific journal
We develop a method for high-speed and high-accuracy first-principles calculations to derive the ground-state electronic structure by directly minimizing the energy functional. Making efficient use of the advantages of the real-space finite-difference method, we apply arbitrary boundary conditions and employ spatially localized orbitals. These advantages enable us to calculate the ground-state electronic structure of a nanostructure sandwiched between crystalline electrodes. The framework of this method and numerical examples for metallic nanowires are presented.
The Japan Institute of Metals and Materials, May 2004, Materials Transactions, 45 (5), 1433 - 1436, English[Refereed]
Scientific journal
- Mar. 2004, Physical Review B, (12), 121408, English
[Refereed]
Scientific journal
- Jan. 2004, Journal of Applied Physics, 95 (3), 1568 - 1571, English
[Refereed]
Scientific journal
In order to yield an atomically flat Si(001) reconstructed surface at as low a temperature as possible, 2-step heating processes after wet cleaning are proposed based on thermal desorption spectroscopy (TDS) spectra. They are pre-annealing at 300°C for 60 min, and subsequent flashing at 650°C. The pre-annealing desorbs one hydrogen atom at each dihydride on the surface, and the flashing desorbs the rest of the hydrogen atoms. Furthermore, for practical device processes, it is proposed that the 2-step heating processes should be performed in a hydrogen ambient to prevent the surface from adsorbing contaminations. Scanning tunneling microscopy (STM) and low energy electron diffraction (LEED) observations reveal that an atomically flat Si(001)-$c(4\times 4)$ surface is obtained by flashing at 650°C in not only ultrahigh vacuum, but also in hydrogen ambient. STM images and first-principles simulations demonstrate that the Si(001)-$c(4\times 4)$ structure is explained by a missing-dimer model.
INSTITUTE OF PURE AND APPLIED PHYSICS, Jul. 2003, Jpn. J. Appl. Phys., 42 (7B), 4646 - 4649, English[Refereed]
Scientific journal
- Jun. 2003, Appl. Phys. Lett., 82 (25), 4570 - 4572, English
[Refereed]
Scientific journal
- Feb. 2003, Nanotechnology, 14 (2), 299 - 303, English
[Refereed]
Scientific journal
- Jan. 2003, Phys. Rev. B, 68 (4), 045409, English
[Refereed]
Scientific journal
We investigate the relation between the geometrical structure and electrical conduction of an infinite single-row gold wire in the process of its elongation using first-principles molecular-dynamics simulations based on the real-space finite-difference method. This relation has not been explicitly explained by experiments yet. Our theoretical study predicts that the single-row gold wire ruptures when the average interatomic distance increases to more than 0.30 nm, and that the wire is conductive before breaking but changes to insulator at the rupturing point.
The Japan Institute of Metals and Materials, Nov. 2001, Mater. Trans. JIM, 42 (11), 2257 - 2260, English[Refereed]
Scientific journal
- Japan Institute of Metals, Nov. 2001, Mater. Trans. JIM, 42 (11), 2257 - 2260, English
[Refereed]
Scientific journal
- Japan Institute of Metals, Nov. 2001, Mater. Trans. JIM, 42 (11), 2247 - 2252, English
[Refereed]
Scientific journal
- Aug. 2001, Physical Review B, 64 (8), 085105, English
[Refereed]
Scientific journal
- Apr. 1999, Physical Review Letters, 82 (25), 5016 - 5019, English
[Refereed]
Scientific journal
- Apr. 1999, Computational Materials Science, 14, 77 - 79, English
[Refereed]
Scientific journal
MISC
- The Physical Society of Japan (JPS), 22 Aug. 2014, Meeting abstracts of the Physical Society of Japan, 69 (2), 176 - 176, Japanese10aAQ-1 Development of high-speed calculation method of Green's function by applying the shift invariance of the Krylov subspace
- The Physical Society of Japan (JPS), 05 Mar. 2012, Meeting abstracts of the Physical Society of Japan, 67 (1), 961 - 961, Japanese26pPSB-23 First-principles investigation on atomic and electronic structure at Ge-MOS interfaces
- The Physical Society of Japan (JPS), 05 Mar. 2012, Meeting abstracts of the Physical Society of Japan, 67 (1), 958 - 958, Japanese26pPSB-11 First-Principles Study on oxygen vacancy of HfO_2/SiO_2/Si Interfaces
- The Physical Society of Japan (JPS), 24 Aug. 2011, Meeting abstracts of the Physical Society of Japan, 66 (2), 628 - 628, Japanese23pTL-1 A design of nanoscale devices using first-principles electron-transport calculation
- The Physical Society of Japan (JPS), 24 Aug. 2011, Meeting abstracts of the Physical Society of Japan, 66 (2), 962 - 962, Japanese24pRC-2 First-principles study on quantum transport through nanoscale systems
- The Physical Society of Japan (JPS), 03 Mar. 2011, Meeting abstracts of the Physical Society of Japan, 66 (1), 943 - 943, Japanese28aTH-1 Synthesis of long gold atom strands incorporated by carbon atoms.
- The Physical Society of Japan (JPS), 03 Mar. 2011, Meeting abstracts of the Physical Society of Japan, 66 (1), 919 - 919, Japanese26pTG-10 First-principles study on quantum transport through nanoscale systems
- The Physical Society of Japan (JPS), 03 Mar. 2011, Meeting abstracts of the Physical Society of Japan, 66 (1), 721 - 721, Japanese27pHG-2 A design of nanoscale devices using first-principles electron-transport calculation
- The Physical Society of Japan (JPS), 18 Aug. 2010, Meeting abstracts of the Physical Society of Japan, 65 (2), 849 - 849, Japanese24aPS-48 First-principles investigation of effective passivants at Ge/GeO_2 interface
- The Physical Society of Japan (JPS), 01 Mar. 2010, Meeting abstracts of the Physical Society of Japan, 65 (1), 961 - 961, Japanese23aGL-9 First-principles study on electron transport through fullerene wires
- The Physical Society of Japan (JPS), 18 Aug. 2009, Meeting abstracts of the Physical Society of Japan, 64 (2), 790 - 790, Japanese28aYE-3 Spin-dependent Transport Properties of Two-dimensional BNC Structures
- The Physical Society of Japan (JPS), 18 Aug. 2009, Meeting abstracts of the Physical Society of Japan, 64 (2), 588 - 588, Japanese26aQL-5 Quantum transport properties of nanoscale systems
- Fundamental Study on GeO_2/Ge Interface and its Electrical Properties
Fundamental aspect of GeO_2/Ge interfaces was investigated by means of first-principles calculations and electrical characterizations of Ge-MOS capacitors. Theoretical study revealed that, due to the high flexibility of the GeO_2 network, intrinsic nature of the Ge-MOS interface is superior to that of Si system. Our systematic experiments also showed that air exposure causing moisture and hydrocarbon adsorption leads to degradation of the MOS devices, but improved electrical properties, such as significantly reduced fixed charge, small hysteresis and minimized minority carrier response, can be obtained by in situ low temperature vacuum annealing prior to gate electrode deposition. The results clearly indicate the inherently superior quality of GeO_2/Ge interface without any interface passivation technique and provide a useful process guideline for achieving Ge-based devices.
The Institute of Electronics, Information and Communication Engineers, 12 Jun. 2009, IEICE technical report, 109 (87), 15 - 20, Japanese - The Physical Society of Japan (JPS), 03 Mar. 2009, Meeting abstracts of the Physical Society of Japan, 64 (1), 908 - 908, Japanese29pPSB-34 First-principles Study on Electron Transport Properties ofthe fullerene dimers
- The Physical Society of Japan (JPS), 03 Mar. 2009, Meeting abstracts of the Physical Society of Japan, 64 (1), 900 - 900, Japanese29pPSB-1 Atomic and electronic structures of germanium dioxide
- The Physical Society of Japan (JPS), 25 Aug. 2008, Meeting abstracts of the Physical Society of Japan, 63 (2), 815 - 815, Japanese21pXA-8 Ab initio study on conductance of 5d metal atomic nanowires
- The Physical Society of Japan (JPS), 25 Aug. 2008, Meeting abstracts of the Physical Society of Japan, 63 (2), 827 - 827, Japanese22pPSA-2 First-Principles Calculation for Transport Properties of Electron through Nano-scale Structures
- The Physical Society of Japan (JPS), 25 Aug. 2008, Meeting abstracts of the Physical Society of Japan, 63 (2), 834 - 834, Japanese22pPSA-34 First-Principles Study on Magnetic Ordering of Al Single-row Atomic Wire
- The Physical Society of Japan (JPS), 29 Feb. 2008, Meeting abstracts of the Physical Society of Japan, 63 (1), 881 - 881, Japanese24pPSA-12 First-Principles Study on Scanning Tunneling Microscopy Image for C_2H_2 absorbed Si(001) Surface
- The Physical Society of Japan (JPS), 29 Feb. 2008, Meeting abstracts of the Physical Society of Japan, 63 (1), 890 - 890, Japanese24pPSA-48 First-Principles Study on Electron-Conduction Properties of Fullerene Polymer
- The Physical Society of Japan (JPS), 21 Aug. 2007, Meeting abstracts of the Physical Society of Japan, 62 (2), 692 - 692, Japanese22aPS-118 First-principles electronic state calculation for fullerene polymers
- The Physical Society of Japan (JPS), 28 Feb. 2007, Meeting abstracts of the Physical Society of Japan, 62 (1), 899 - 899, Japanese20aPS-19 First-Principles Study on Scanning Tunneling Microscopy Image for C_2H_2 absorbed Si(001) Surface
- The Physical Society of Japan (JPS), 18 Aug. 2006, Meeting abstracts of the Physical Society of Japan, 61 (2), 763 - 763, Japanese25pPSB-66 An electronic structure calculation of peanut-shaped fullerene tubes
- The Physical Society of Japan (JPS), 04 Mar. 2006, Meeting abstracts of the Physical Society of Japan, 61 (1), 915 - 915, Japanese30pXJ-11 First-principles study on electron conduction properties of nanowire array
- The Physical Society of Japan (JPS), 04 Mar. 2006, Meeting abstracts of the Physical Society of Japan, 61 (1), 890 - 890, Japanese29pXJ-9 First-principles Calculation for Electronic Structures of Nanostructures Suspended between Semi-infinite Crystalline Electrodes
- The Physical Society of Japan (JPS), 04 Mar. 2006, Meeting abstracts of the Physical Society of Japan, 61 (1), 291 - 291, Japanese28pXH-1 Macroscopic Polarization of AlN nanotubes from Wannier functions
- The Physical Society of Japan (JPS), 04 Mar. 2005, Meeting abstracts of the Physical Society of Japan, 60 (1), 881 - 881, Japanese27aXD-7 First-principles study on conductance oscillation in single-row nanowires.
- The Physical Society of Japan (JPS), 04 Mar. 2005, Meeting abstracts of the Physical Society of Japan, 60 (1), 854 - 854, Japanese25aWB-1 Analysis of leakage current through a silicon oxide film using first-principles electron transoprt calcualtion
- The Physical Society of Japan (JPS), 04 Mar. 2005, Meeting abstracts of the Physical Society of Japan, 60 (1), 854 - 854, Japanese25aWB-2 First-principles Calculation Method for Electronic Structures of nanostructures Suspended between Semi-infinite Crystalline Electrodes
- The Physical Society of Japan (JPS), 04 Mar. 2005, Meeting abstracts of the Physical Society of Japan, 60 (1), 320 - 320, Japanese27aPS-9 Macroscopic Polarization from Wannier functions
- The Physical Society of Japan (JPS), 04 Mar. 2005, Meeting abstracts of the Physical Society of Japan, 60 (1), 836 - 836, Japanese24aPS-134 First-Principles study on the Scanning Tunneling Microscopy Image of hydrogen-adsorbed Si(001)
- The Physical Society of Japan (JPS), 03 Mar. 2004, Meeting abstracts of the Physical Society of Japan, 59 (1), 901 - 901, Japanese27pPSA-54 First-principles study on leak currents through silicon oxide film
- The Physical Society of Japan (JPS), 03 Mar. 2004, Meeting abstracts of the Physical Society of Japan, 59 (1), 901 - 901, Japanese27pPSA-52 First-principles study on conduction properties of nanosutructures
- The Physical Society of Japan (JPS), 03 Mar. 2004, Meeting abstracts of the Physical Society of Japan, 59 (1), 889 - 889, Japanese27pPSA-6 Development of order-N method of first-principles electronic-structure calculation II
- The Physical Society of Japan (JPS), 03 Mar. 2004, Meeting abstracts of the Physical Society of Japan, 59 (1), 934 - 934, Japanese30pWP-2 First-principles study of electron conduction through metallic nanowire
- 大阪大学低温センター, Jan. 2004, 大阪大学低温センターだより, 125, 31 - 34, Japanese強電界下における表面反応の第一原理分子動力学シミュレーション
- The Physical Society of Japan (JPS), 15 Aug. 2003, Meeting abstracts of the Physical Society of Japan, 58 (2), 794 - 794, JapaneseDevelopment of order-N method of first-principles electronic-structure calculation
- The Physical Society of Japan (JPS), 15 Aug. 2003, Meeting abstracts of the Physical Society of Japan, 58 (2), 793 - 793, JapaneseFirst-principles study of electron conduction through metallic nanowire
- The Physical Society of Japan (JPS), 15 Aug. 2003, Meeting abstracts of the Physical Society of Japan, 58 (2), 794 - 794, JapaneseElectric properties of fullerene chain II
- The Physical Society of Japan (JPS), 15 Aug. 2003, Meeting abstracts of the Physical Society of Japan, 58 (2), 795 - 795, JapaneseFirst-principles study on conduction properties of sodium nanowire
- The Physical Society of Japan (JPS), 15 Aug. 2003, Meeting abstracts of the Physical Society of Japan, 58 (2), 264 - 264, JapaneseFirst-principles molecular-dynamics simulation of the process of water decomposition
- The Physical Society of Japan (JPS), 06 Mar. 2003, Meeting abstracts of the Physical Society of Japan, 58 (1), 862 - 862, JapaneseAnalysis of photo-reflectance difference between two silicon surfaces with different surface orientation : Comparison between (100) and (111)
- The Physical Society of Japan (JPS), 06 Mar. 2003, Meeting abstracts of the Physical Society of Japan, 58 (1), 858 - 858, JapaneseProton relays between Nafion and waters using ab-initio molecular dynamics simulation
- The Physical Society of Japan (JPS), 06 Mar. 2003, Meeting abstracts of the Physical Society of Japan, 58 (1), 860 - 860, JapaneseElectrical Analyses of Fullererie Chains by First-Principles Calculations
- The Physical Society of Japan (JPS), 06 Mar. 2003, Meeting abstracts of the Physical Society of Japan, 58 (1), 857 - 857, JapaneseFirst-principles sutudy on conduction properties of nanotube
- The Physical Society of Japan (JPS), 06 Mar. 2003, Meeting abstracts of the Physical Society of Japan, 58 (1), 886 - 886, JapaneseStructure and conductance of single atom metal wire III
- The Physical Society of Japan (JPS), 13 Aug. 2002, Meeting abstracts of the Physical Society of Japan, 57 (2), 749 - 749, JapaneseFirst-principles molecular-dynamics simulations for plasma etching of Si surface using halogen gases : Analysis of the promotional generation of halogen radical by oxygen radical
- The Physical Society of Japan (JPS), 01 Mar. 2002, Meeting abstracts of the Physical Society of Japan, 57 (1), 848 - 848, Japanese25pPSB-52 First-principles molecular-dynamics simulation for metal surface atometched by OH
- The Physical Society of Japan (JPS), 01 Mar. 2002, Meeting abstracts of the Physical Society of Japan, 57 (1), 851 - 851, Japanese25pPSB-64 Structure and conductance of one-dimensional fullerene polymer
- The Physical Society of Japan (JPS), 01 Mar. 2002, Meeting abstracts of the Physical Society of Japan, 57 (1), 867 - 867, Japanese27aYF-10 The electron transport properties of an atomic wire for Au.
- The Physical Society of Japan (JPS), 01 Mar. 2002, Meeting abstracts of the Physical Society of Japan, 57 (1), 868 - 868, Japanese27aYF-11 Structure and conductance of single atom metal wire II
- The Physical Society of Japan (JPS), 03 Sep. 2001, Meeting abstracts of the Physical Society of Japan, 56 (2), 773 - 773, JapaneseFirst-principles calculation of electron transport for alkali metal nanowire
- The Physical Society of Japan (JPS), 03 Sep. 2001, Meeting abstracts of the Physical Society of Japan, 56 (2), 773 - 773, JapaneseStructure and conductance of single atom metal wire
- The Physical Society of Japan (JPS), 03 Sep. 2001, Meeting abstracts of the Physical Society of Japan, 56 (2), 773 - 773, JapaneseThe electron transport properties of an atomic wire for Au.
- The Physical Society of Japan (JPS), 03 Sep. 2001, Meeting abstracts of the Physical Society of Japan, 56 (2), 768 - 768, JapaneseAb Initio Study of the Reaction Mechanism of Water Dissociation based on Real Space Finite Difference
- 01 Sep. 2001, 精密工学会大会学術講演会講演論文集, 2001 (2), 672 - 672, Japanese光反射率スペクトルによるSiウエハ表面評価法の開発 : 装置の開発と加工表面評価
- 01 Sep. 2001, 精密工学会大会学術講演会講演論文集, 2001 (2), 226 - 226, Japanese超純水のみによる電気化学的加工法の第一原理分子動力学シミュレーション : 陰極におけるA1(001)表面加工現象
- 01 Sep. 2001, 精密工学会大会学術講演会講演論文集, 2001 (2), 235 - 235, JapaneseハロゲンによるSi表面エッチング過程の第一原理分子動力学シミュレーション : エッチング過程とガス材料依存性
- The Physical Society of Japan (JPS), 09 Mar. 2001, Meeting abstracts of the Physical Society of Japan, 56 (1), 223 - 223, JapaneseAb-initio electronic-structure calculation using real-space finite-difference method with spiral boundary condition.
- The Physical Society of Japan (JPS), 10 Sep. 2000, Meeting abstracts of the Physical Society of Japan, 55 (2), 790 - 790, JapaneseSolution for the fractional occupation problem in metallic system.
- The Physical Society of Japan (JPS), 10 Mar. 2000, Meeting abstracts of the Physical Society of Japan, 55 (1), 221 - 221, JapaneseCalculation of the surface states based on real-space finite-difference scheme using timesaving double-grid method II
- The Physical Society of Japan (JPS), 03 Sep. 1999, Meeting abstracts of the Physical Society of Japan, 54 (2), 229 - 229, Japanese25aPS-38 Minimization of Electronic-energy functional
- The Physical Society of Japan (JPS), 03 Sep. 1999, Meeting abstracts of the Physical Society of Japan, 54 (2), 229 - 229, Japanese25aPS-37 Analysis of Dissociation Process of Water Molecule Using Real-Space Finite-Difference Method
- The Physical Society of Japan (JPS), 03 Sep. 1999, Meeting abstracts of the Physical Society of Japan, 54 (2), 841 - 841, Japanese27pW-4 Calculation of the surface states based on real-space finite-diference scheme using timesaving double-grid method
- The Physical Society of Japan (JPS), 05 Sep. 1998, Meeting abstracts of the Physical Society of Japan, 53 (2), 809 - 809, JapaneseAb initio molecular dynamics aimulation using real-space finite difference method
- The Physical Society of Japan (JPS), 05 Sep. 1998, Meeting abstracts of the Physical Society of Japan, 53 (2), 811 - 811, JapaneseMinimization of Electronic structure energy using Simulated Annealing method
- The Physical Society of Japan (JPS), 10 Mar. 1998, Meeting abstracts of the Physical Society of Japan, 53 (1), 640 - 640, JapaneseElectronic-atructuer calculating using real-space finite difference method based on GGA III
- The Physical Society of Japan (JPS), 16 Sep. 1997, Meeting abstracts of the Physical Society of Japan, 52 (2), 349 - 349, Japanese6p-B-2 Calculation of electronic-structures in a strong electric field under the STM-XMA condition
- The Physical Society of Japan (JPS), 16 Sep. 1997, Meeting abstracts of the Physical Society of Japan, 52 (2), 331 - 331, Japanese5a-B-4 First-principles study of etching of the hydrogen-terminated Si(001)surface interacting with OH molecule(I)
- The Physical Society of Japan (JPS), 16 Sep. 1997, Meeting abstracts of the Physical Society of Japan, 52 (2), 807 - 807, Japanese8a-YJ-8 Electronic-structure calculations using real-space finite difference method based on GGA II
- The Physical Society of Japan (JPS), 17 Mar. 1997, Meeting abstracts of the Physical Society of Japan, 52 (1), 716 - 716, Japanese30p-YH-15 Electronic-structute calculations using real-space finite difference method based on GGA I
Books etc
- Contributor, 表面界面物性シミュレーション, Mar. 2014, Japanese超精密加工と表面科学
Scholarly book
- Contributor, Real Space Electronic Structure Calculation Code (RSPACE-04) - Nanowire Conductance Related Studies -, 大阪大学出版会, Sep. 2005, JapaneseIntroduction to Computational Materials Design -From the Basics to Actual Applications-
Scholarly book
- Contributor, Real Space Electronic Structure Calculation Code (RSPACE-04), 大阪大学出版会, Jan. 2005, JapaneseIntroduction to Computational Materials Design -From the Basics to Actual Applications-
Scholarly book
- Single work, Jan. 2005, EnglishFIRST-PRINCIPLES CALCULATIONS IN REAL-SPACE FORMALISM --Electronic Configurations and Transport Properties of Nanostructures--
Scholarly book
Presentations
- European Advanced Energy Materials Congress, 25 Mar. 2018, English, International conferenceDFT calculation for electronic structure and carrier scattering property at SiC-MOS interface
[Invited]
Invited oral presentation
- International Conference for High Performance Computing, Networking, Storage and Analysis (SC17), 13 Nov. 2017, English, International conferenceEfficient and Scalable Calculation of Complex Band Structure Using Sakurai-Sugiura Method
Oral presentation
- 日本物理学会2017年秋季大会, 21 Sep. 2017, Japanese, Domestic conference第一原理計算によるデバイス用界面の電子状態とキャリア伝導解析
[Invited]
Invited oral presentation
- 2017 Meeting of the International Linear Algebra Society, 24 Jul. 2017, English, International conferenceNonlinear Sakurai-Sugiura method for electronic transport calculation
Oral presentation
- The Platform for Advanced Scientific Compuging (PASC) Conference, 26 Jun. 2017, English, International conferenceNonlinear Sakurai-Sugiura method for complex band structure calculation on KNL cluster
Oral presentation
- EMN Meeting on Quantum, 18 Jun. 2017, English, International conferenceDensity functional theory calculation for interface electronic structure of SiC power electronic devices
[Invited]
Invited oral presentation
- 情報機構セミナー, 13 Jun. 2017, Japanese, Domestic conference第一原理計算と高速計算機を用いた材料探索・デバイス設計
[Invited]
Invited oral presentation
- APS March Meeting 2017, 13 Mar. 2017, English, International conferenceFirst-principles study on atomic and electronic structures of 4HSiC(0001)/SiO interface
Oral presentation
- Symposium on Semiconductors, Dielectrics, and Metals for Nanoelectronics 14 held during the PRiME Joint Int Meeting of The Electrochemical-Society, The Electrochemical-Society-of-Japan, and the Korean-Electrochemical-Society, 02 Oct. 2016, English, Honolulu, HI, International conferenceFirst-Principles Study on Electron Conduction at 4H-SiC(0001)/SiO2 Interface
[Invited]
Invited oral presentation
- 2016 International Conference on Solid State Devices and Materials, 26 Sep. 2016, English, Domestic conferenceFirst-principles study on carrier scattering property at 4H-SiC(0001)/SiO2
Oral presentation
- 応用物理学会先進パワー半導体分科会 第1回個別討論会 「SiC酸化メカニズムと界面欠陥」, 04 Aug. 2016, Japanese, 日本 東京, Domestic conferenceSiC酸化過程とMOS界面電子状態の第一原理シミュレーション
[Invited]
Invited oral presentation
- 5th International Conference from Nanoparticles and Nanomaterials to Nanodevices and Nanosystems (IC4N), 26 Jun. 2016, English, International conferenceDensity functional theory study on transport property of nanomaterials
[Invited]
Invited oral presentation
- EMN Meeting on Carbon Nanostructures, 27 Mar. 2016, English, USA Honolulu, International conferenceDensity functional theory calculation for transport property of carbon nanostructures
[Invited]
Invited oral presentation
- International Workshop on Dielectric Thin Films for Future Electron Devices – Science and Technology –, 02 Nov. 2015, English, Japan Tokyo, Domestic conferenceAb initio investigations for interface electronic structures of SiC-MOS
[Invited]
Invited oral presentation
- Advances in Modeling of Nano Materials, 14 Jun. 2015, English, China Hefei, International conferenceFirst-Principles Calculations using Real-Space Finite-Difference Method
[Invited]
Invited oral presentation
- 応用物理学会関西支部平成26年度第2回講演会「シミュレーションが先導するエレクトロニクス・フォトニクス研究 ～関西発イノベーションと若手からの発信～」, 12 Nov. 2014, Japanese, Domestic conference第一原理計算を用いたナノデバイスの機能予測
[Invited]
Invited oral presentation
- International Workshop of Computational Nano-Materials Design on Green Energy, JSPS Core-to-Core Program Workshop, 01 Jun. 2014, English, Japan Osaka, Domestic conferenceFirst-principles calculation on transport properties of carbon nanotubes and fullerenes
[Invited]
Invited oral presentation
Association Memberships
THE PHYSICAL SOCIETY OF JAPAN
The Japan Society of Applied Physics
The Surface Science Society of Japan
Research Projects
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Transformative Research Areas (A), Grant-in-Aid for Transformative Research Areas (A), Kobe University, Jun. 2022 - Mar. 2024Investigation of carrier transport in 2-dimensional nano space and design of highly functional device by computational science approach
- 日立財団, 倉田奨励金, 神戸大学, Apr. 2020 - Mar. 2021, Principal investigator量子論に基づくシミュレーションによる高移動度SiC-MOS界面とその創製プロセスの設計
- (財)岩谷直治記念財団, 岩谷科学技術研究助成, 神戸大学, Apr. 2020 - Mar. 2021, Principal investigator計算科学による高移動度SiC-MOS界面構造のデザイン
- ひょうご科学技術協会, 学術研究助成, 神戸大学, Apr. 2020 - Mar. 2021, Principal investigator超並列計算機用デバイス機能予測シミュレーターの開発
- 日本学術振興会, 科学研究費 基盤研究(B), Apr. 2016 - Mar. 2020, Principal investigator大規模第一原理スピン輸送シミュレーターの開発と革新的デバイス用界面構造の設計
Competitive research funding
- 筑波大学, 筑波大学・DAADパートナーシップ・プログラム, 筑波大学, Apr. 2018 - Mar. 2019, Principal investigator大規模物質・デバイス設計シミュレーションを目指した第一原理計算コードの開発
- Japan Science and Technolgy Agency, PRESTO, Oct. 2013 - Mar. 2017, Principal investigatorComputational design of interfaces for low energy consumption power electronic devices
Competitive research funding
- 日本学術振興会, 科学研究費 若手研究(B), Apr. 2012 - Mar. 2014, Principal investigator第一原理計算による高効率量子輸送デバイスのデザイン
Competitive research funding
- Japan Science and Technology Agency, Strategic International Research Cooperative Program, Aug. 2009 - Mar. 2013, Principal investigatorComputational design and evaluation of spintronics materials
Competitive research funding
- 日本学術振興会, 科学研究費 若手研究(B), Apr. 2008 - Mar. 2011, Principal investigator第一原理量子輸送計算による高機能界面ナノ構造の設計
Competitive research funding
- 日本学術振興会, 科学研究費 若手研究(B), Apr. 2005 - Mar. 2008, Principal investigator第一原理計算による分子スケールデバイスの設計
Competitive research funding
- (財)大阪大学後援会, 教育研究助成金, 大阪大学, Apr. 2005 - Mar. 2006, Principal investigator第一原理計算によるナノスケール構造の機能予測
- 日本学術振興会, 科学研究費 若手研究(B), Apr. 2002 - Mar. 2005, Principal investigator第一原理分子動力学計算による原子・分子細線の機能予測
Competitive research funding
- 文部科学省, 科学研究費補助金 特別研究員奨励費, Apr. 2000 - Mar. 2001, Principal investigator実空間差分法による超純水電気化学加工の第一原理分子動力学計算
Competitive research funding