95 citations · 490 across the 16 of their papers we have counts for
16 papers
Energetics and electronic structure of native point defects in -Ga2O3
Takuma Kobayashi, Tomoya Gake, Yu Kumagai +2
We report first-principles calculations that clarify the formation energies and charge transition levels of native point defects (Ga and O vacancies, interstitials, and a Ga vacanc…
Native point defects and carbon clusters in 4H-SiC: A hybrid functional study
Takuma Kobayashi, Kou Harada, Yu Kumagai +2
We report first-principles calculations that clarify the formation energies and charge transition levels of native point defects and carbon clusters in the 4H polytype of silicon c…
Structure and energetics of carbon-related defects in SiC (0001)/SiO systems revealed by first-principles calculations: Defects in SiC, SiO, and just at their interface
Takuma Kobayashi, Yu-ichiro Matsushita
We report first-principles calculations that reveal the atomic forms, stability, and energy levels of carbon-related defects in SiC (0001)/SiO systems. We clarify the sta…
Structural stability and energy levels of carbon-related defects in amorphous SiO and its interface with SiC
Yu-ichiro Matsushita, Atsushi Oshiyama
We report the density-functional calculations that systematically clarify the stable forms of carbon-related defects and their energy levels in amorphous SiO using the melt-que…
Unfolding energy spectra of multi-periodicity materials
Yu-ichiro Matsushita, Hirofumi Nishi, Jun-ichi Iwata +2
We propose a new unfolding scheme to analyze energy spectra of complex large-scale systems which are inherently of multi-periodicity. Considering twisted bilayer graphene (tBLG) as…
Analysis of single and composite structural defects in pure amorphous silicon: a first-principles study
Yoritaka Furukawa, Yu-ichiro Matsushita
The structural and electronic properties of amorphous silicon (-Si) are investigated by first-principles calculations based on the density-functional theory (DFT), focusing on t…
A novel intrinsic interface state controlled by atomic stacking sequence at interfaces of SiC/SiO
Yu-ichiro Matsushita, Atsushi Oshiyama
On the basis of ab-initio total-energy electronic-structure calculations, we find that interface localized electron states at the SiC/SiO interface emerge in the energy region…
First-Principles Prediction of Densities of Amorphous Materials: The Case of Amorphous Silicon
Yoritaka Furukawa, Yu-ichiro Matsushita
A novel approach to predict the atomic densities of amorphous materials is explored on the basis of Car-Parrinello molecular dynamics (CPMD) in density functional theory. Despite t…
Microscopic Mechanism of Carbon Annihilation upon SiC Oxidation due to Phosphorous Treatment: Density-Functional Calculations Combined with Ion Mass Spectrometry
Takuma Kobayashi, Yu-ichiro Matsushita, Takafumi Okuda +2
We report first-principles static and dynamic calculations that clarify the microscopic mechanism of carbon annihilation due to phosphorous treatment upon oxidation of silicon carb…
Comprehensive study on band-gap variations in -bonded semiconductors: roles of electronic states floating in internal space
Yu-ichiro Matsushita, Atsushi Oshiyama
We have performed electronic structure calculations to explore the band-gap dependence on polytypes for -bonded semiconducting materials, i.e., SiC, AlN, BN, GaN, Si, and dia…
Mechanisms of initial oxidation of 4H-SiC (0001) and (000) surfaces unraveled by first-principles calculations
Yu-ichiro Matsushita, Atsushi Oshiyama
We have performed electronic state calculations to clarify the initial stage of the oxidation of the Si- and C-faces in 4H-SiC based on the density-functional theory. We investigat…
First-principles calculations that clarify energetics and reactions of oxygen adsorption and carbon desorption on 4H-SiC () surface
Han Li, Yu-ichiro Matsushita, Mauro Boero +1
We report static and dynamic first-principles calculations that provide atomistic pictures of the initial stage of the oxidation processes occurring at the () surface of…
Band-unfolding approach to Moirè-induced band-gap opening and Fermi-level-velocity reduction in twisted bilayer graphene
Hirofumi Nishi, Yu-ichiro Matsushita, Atsushi Oshiyama
We report on the energy spectrum of electrons in twisted bilayer graphene (tBLG) obtained by the band-unfolding method in the tight-binding model. We find the band-gap opening at p…
L1 stacked binaries as candidates for hard magnets: FePt, MnAl and MnGa
Yu-ichiro Matsushita, Galia Madjarova, C. Felser +3
A novel strategy of stacking binary magnets to enhance the magneto crystalline anisotropy is explored. This strategy is used in the search for hard magnets by studying FePt/MnGa an…
Interstitial Channels that Control Band Gaps and Effective Masses in Tetrahedrally Bonded Semiconductors
Yu-ichiro Matsushita, Atsushi Oshiyama
We find that electron states at the bottom of the conduction bands of covalent semiconductors are distributed mainly in the interstitial channels and that this floating nature lead…
Comparative study of hybrid functionals applied to structural and electronic properties of semiconductors and insulators
Yu-ichiro Matsushita, Kazuma Nakamura, Atsushi Oshiyama
We present a systematic study that clarifies validity and limitation of current hybrid functionals in density functional theory for structural and electronic properties of various…