A5001500059- Silicon Carbide Semiconductor Technologies
- Semiconductor materials and devices
- Thin-Film Transistor Technologies
- Silicon and Solar Cell Technologies
- Physics of Superconductivity and Magnetism
- Diamond and Carbon-based Materials Research
- Silicon Nanostructures and Photoluminescence
- Integrated Circuits and Semiconductor Failure Analysis
- Solidification and crystal growth phenomena
- Aluminum Alloy Microstructure Properties
- Semiconductor materials and interfaces
- Metallurgical Processes and Thermodynamics
- Copper Interconnects and Reliability
- Advancements in Semiconductor Devices and Circuit Design
- Advancements in Battery Materials
- Advanced ceramic materials synthesis
- Fullerene Chemistry and Applications
- Magnetic and transport properties of perovskites and related materials
- Ga2O3 and related materials
- X-ray Spectroscopy and Fluorescence Analysis
- High-pressure geophysics and materials
- Aluminum Alloys Composites Properties
- Nuclear Physics and Applications
- Superconducting Materials and Applications
- Advanced Condensed Matter Physics
University of Tsukuba
2014-2024
Sumitomo Electric Industries (Japan)
2024
National Institute of Advanced Industrial Science and Technology
2011-2016
Sumitomo Chemical (Japan)
2010-2013
University of Hyogo
2012
Chulalongkorn University
2005-2011
Ryukoku University
2007
Osaka City University
2005
Osaka University
1989-2005
Osaka Medical and Pharmaceutical University
2005
We report the experimental realization of a hybrid quantum circuit combining superconducting qubit and an ensemble electronic spins. The qubit, transmon type, is coherently coupled to spin consisting nitrogen-vacancy (NV) centers in diamond crystal via frequency-tunable resonator acting as bus. Using this circuit, we prepare arbitrary superpositions states that store into collective excitations retrieve back later on qubit. These results constitute first proof concept spin-ensemble based...
Using electron paramagnetic resonance (EPR), energy levels of the carbon vacancy (${V}_{C}$) in $4H$-SiC and its negative-$U$ properties have been determined. Combining EPR deep-level transient spectroscopy we show that two most common defects as-grown $4H$-SiC---the ${Z}_{1/2}$ lifetime-limiting defect $E{H}_{7}$ deep defect---are related to double acceptor ($2\ensuremath{-}|0$) single donor ($0|+$) ${V}_{C}$, respectively.
Electron paramagnetic resonance and ab initio supercell calculations suggest that the P6/P7 centers, which were previously assigned to photoexcited triplet states of carbon vacancy-antisite pairs in double positive charge state, are related ground neutral divacancy. The spin density is found be located mainly on three nearest C neighbors silicon vacancy, whereas it negligible Si vacancy.
Spins of negatively charged nitrogen-vacancy (NV${}^{\ensuremath{-}}$) defects in diamond are among the most promising candidates for solid-state qubits. The fabrication quantum devices containing these spin-carrying requires position-controlled introduction NV${}^{\ensuremath{-}}$ having excellent properties such as spectral stability, a long spin coherence time, and stable negative charge state. Nitrogen ion implantation annealing enable positioning qubits with high precision, but to date,...
Quantum computing promises to tackle computational problems that are intractable with classical computers. Researchers demonstrate spin ensembles can store quantum information over longer times than previously achieved, a significant step toward memory.
Nitrogen atoms fixed in the SiO2/SiC interface region were studied by x-ray photoelectron spectroscopy (XPS) and capacitance-voltage (C-V) measurements. A thin oxide film (<5 Å) formed during annealing an NO atmosphere on a (0001) 4H-SiC surface, incorporating nitrogen into region. Even after complete removal of layer etching hydrofluoric acid, XPS spectra clearly showed strong N 1 s peak, revealing presence with areal density 1014 cm−2 To evaluate their influence traps,...
Single defects in diamond and especially negatively charged nitrogen vacancy (NV) centers are very promising quantum systems with wide applications physics biology. It was shown that their coherence properties can be strongly improved by growing ultrapure low concentration of parasitic spins associated electron nuclear related to $^{13}$C carbon isotope. Here we report a high quality $^{12}$C-enriched polycrystalline CVD material comparable single crystals. We find NVs the grains this...
The metastability of vacancies was theoretically predicted for several compound semiconductors alongside their transformation into the antisite-vacancy pair counterpart; however, no experiment to date has unambiguously confirmed existence pairs. Using electron paramagnetic resonance and first principles calculations we identify $SI5$ center as carbon in negative charge state (${\mathrm{C}}_{\mathrm{Si}}{V}_{\mathrm{C}}^{\ensuremath{-}}$) $4H$-SiC. We suggest that this defect is a strong...
Abstract The structure determination of intrinsic defects in 4H‐SiC, 6H‐SiC, and 3C‐SiC by means EPR is based on measuring the angular dependence 29 Si/ 13 C hyperfine (HF) satellite lines, from which spin densities, sp‐hybrid ratio, p‐orbital direction can be determined over major atoms comprising a defect. In most cases, not only assignment variety due to inequivalent sites ( h ‐ k ‐sites 4H‐SiC) but also identification defect species accomplished through comparison obtained HF parameters...
The microscopic behavior of nitrogen atoms in the SiO2-SiC interface regions n-channel lateral 4 H-SiC metal-oxide-semiconductor field effect transistors (MOSFETs) was studied using low-temperature electrically detected magnetic resonance spectroscopy and other techniques. results show that eliminated shallow states observable at 20 K further diffused into channel region MOSFETs as donors. These two behaviors enable to change conductivity SiC MOSFETs.
This article reviews efforts to build a new type of quantum device, which combines an ensemble electronic spins with long coherence times, and small-scale superconducting processor. The goal is store over times arbitrary qubit states in orthogonal collective modes the spin-ensemble, retrieve them on-demand. We first present protocol devised for such multi-mode memory. then describe series experimental results using NV center diamond, demonstrate its main building blocks: transfer from into...
A new method for detecting the magnetic resonance of electronic spins at low temperature is demonstrated. It consists in measuring signal emitted by with a superconducting qubit that acts as single-microwave-photon detector, resulting an enhanced sensitivity. We implement such electron-spin spectrometer using hybrid quantum circuit which transmon coupled to spin ensemble consisting nitrogen-vacancy (NV) centers diamond. With this setup we measure NV center absorption spectrum 30 mK...
NCVSi− centers in SiC [nitrogen-vacancy (NV) centers], which produce near-infrared (NIR) photoluminescence (PL) at room temperature, is expected to have applications as quantum sensors for vivo imaging and sensing. To realize sensing using NV centers, clarification of the formation mechanism well control high-density necessary. This paper reports a comprehensive investigation on NIR-PL properties originating from high purity semi-insulating nitrogen (N) contained 4H-SiC substrates formed by...
The carbon vacancy is a dominant defect in $4H\text{\ensuremath{-}}\mathrm{Si}\mathrm{C}$, and the ``EI5'' electron-paramagnetic-resonance (EPR) spectrum originates from positively charged vacancies $(V_{\mathrm{C}}{}^{+})$ at quasicubic sites. observed state for EI5, however, has been attributed to motional-averaged with ${C}_{3\mathrm{v}}$ symmetry, its true atomic structure not revealed so far. We here report low temperature $(<40\phantom{\rule{0.3em}{0ex}}\mathrm{K})$ EPR measurements on...
Carbon vacancies $({\mathrm{V}}_{\mathrm{C}})$ are typical intrinsic defects in silicon carbides (SiC) and so far have been observed only the form of positively charged states $p$-type or semi-insulating SiC. Here, we present electron-paramagnetic-resonance (EPR) photoinduced EPR (photo-EPR) observations their negatively state $({\mathrm{V}}_{\mathrm{C}}^{\ensuremath{-}})$ $n$-type $4H\text{\ensuremath{-}}\mathrm{Si}\mathrm{C}$. This center (called HEI1) is characterized by an electron spin...
In this paper, we unambiguously re-determine the spin multiplicity of ${T}_{V2a}$ by pulsed electron nucleus double resonance technique. The center is one most commonly observed defects in $4H$-SiC, and its origin was identified as belonging to a class negatively charged silicon vacancy means continuous-wave paramagnetic (EPR) two-dimensional nutation method EPR However, model with triplet $(S=1)$ neutral charge state has recently been suggested. Our result clearly shows that quartet...
An antisite-vacancy pair and a monovacancy are set of fundamental stable and/or metastable defects in compound semiconductors. Theory predicted that carbon pairs would be much more $p$-type SiC than silicon vacancies they common defect. However, no experimental evidence has yet supported this prediction. We reexamine electron-irradiated $4H\text{\ensuremath{-}}\mathrm{Si}\mathrm{C}$ identify the positively charged $({\mathrm{C}}_{\mathrm{Si}}V_{\mathrm{C}}{}^{+})$ by means electron...
We present single photon sources (SPSs) embedded in 4H-SiC metal-oxide-semiconductor field-effect transistors (MOSFETs). They are formed the SiC/SiO2 interface regions of wet-oxidation C-face MOSFETs and were not found other Si-face MOSFETs. Their bright room-temperature photoluminescence (PL) was observed range from 550 to 750 nm revealed variable multi-peak structures as well peak shifts. characterized a wide variety their PL spectra inevitable variation local atomic at interface....
We identify a carbon dangling-bond center intrinsically formed at thermally oxidized 4H-SiC(0001)/SiO2 interfaces. Our electrically detected-magnetic-resonance spectroscopy and first-principles calculations demonstrate that this center, which we name “the PbC center,” is adatom on the 4H-SiC(0001) honeycomb-like structure. The (Si3≡C-, where “-” represents an unpaired electron) determined to be just version of famous Pb (Si Si3≡Si-) Si(111)/SiO2 interfaces because found close similarities...
A variety of electron-spin-resonance (ESR) spectra dangling bond $(g=2.0055)$ in undoped hydrogenated amorphous silicon $(a\ensuremath{-}\mathrm{S}\mathrm{i}:\mathrm{H})$ have been measured by the echo-detected ESR pulsed as well usual continuous-wave (cw) for a wide range two experimental parameters microwave frequency $(\ensuremath{\nu}=3--34\mathrm{GHz})$ and ${}^{29}\mathrm{Si}$ content ($p=1.6,$ 4.7, 9.1 at. %). Using those spectra, we carried out spectral simulations on whole spectrum...
The EI5 and EI6 centers are typical intrinsic defects in radiation-damaged semi-insulating $4H\ensuremath{-}\mathrm{SiC}.$ So far, their origins have been assigned to positively charged carbon vacancies ${(V}_{\mathrm{C}}^{+})$ silicon antisites $({\mathrm{Si}}_{\mathrm{C}}^{+}),$ respectively. However, our complete set of ${}^{29}\mathrm{Si}$ hyperfine (HF) data clearly reveals that both the should originate from ${V}_{\mathrm{C}}^{+}$ but locations different, i.e., quasicubic sites for...
We investigated a metal-oxide-semiconductor interface of dry-oxidized (0001¯) 4H-SiC, which was known as the most electrically deteriorated SiC MOSFET, by detected magnetic resonance (EDMR) and observed signal with an isotropic g factor (2.0024) magnetic-field angular dependent widths. Judging from factor, comes sp2-bonded carbon clusters. In addition, we found that dependence EDMR widths caused two-dimensional dipolar broadening exchange interaction between electron spins. However, density...