A5021972788- Semiconductor materials and devices
- Advanced Condensed Matter Physics
- Advancements in Semiconductor Devices and Circuit Design
- Topological Materials and Phenomena
- Integrated Circuits and Semiconductor Failure Analysis
- Advanced Memory and Neural Computing
- Magnetic and transport properties of perovskites and related materials
- Physics of Superconductivity and Magnetism
- Electronic and Structural Properties of Oxides
- Graphene research and applications
- Silicon Carbide Semiconductor Technologies
- Atomic and Subatomic Physics Research
- 2D Materials and Applications
- Magnetic properties of thin films
- Ferroelectric and Negative Capacitance Devices
- High-pressure geophysics and materials
- Characterization and Applications of Magnetic Nanoparticles
- Quantum, superfluid, helium dynamics
- Electromagnetic Compatibility and Noise Suppression
- Nanoporous metals and alloys
- HVDC Systems and Fault Protection
- Seismic Waves and Analysis
- Graphite, nuclear technology, radiation studies
- Food Drying and Modeling
- Low-power high-performance VLSI design
The University of Tokyo
1962-2025
Japan Science and Technology Agency
2022
RIKEN Center for Emergent Matter Science
2022
Hitachi (Japan)
2002-2016
Renesas Electronics (Japan)
2007
University of California, Berkeley
2003
Hitachi (United States)
2002
Abstract Van-der-Waals magnetic materials can be exfoliated to realize ultrathin sheets or interfaces with highly controllable optical spintronics responses. In majority, these are collinear ferro-, ferri-, antiferromagnets, a particular scarcity of lattice-incommensurate helimagnets defined left- right-handed rotation sense, helicity. Here, we report polarized neutron scattering experiments on DyTe 3 , whose layered structure has metallic tellurium layers separated by double-slabs...
Abstract Electrons in conventional metals become less mobile under the influence of electron correlation. Contrary to this empirical knowledge, we report here that electrons with highest mobility ever found known bulk oxide semiconductors emerge strong-correlation regime Dirac semimetal perovskite CaIrO 3 . The transport measurements reveal high exceeding 60,000 cm 2 V −1 s originates from proximity Fermi energy node (ΔE < 10 meV). calculation based on density functional theory and...
Antiferromagnets with spin splitting in the electronic structure are desired for novel spintronic phenomena materials nearly zero net magnetization. One of simplest spin-split antiferromagnetic states, $p$-wave magnet, is proposed as a result collective instability electron gases. Following more recent theoretical proposal without strong correlations, we here report material symmetry constraints magnetism conduction electrons momentum space, based on texture magnetic moments direct space....
The electronic structure of compensated antiferromagnets (CAF) creates large functional responses, reminiscent ferromagnets and suitable for data storage readout, despite (nearly) net-zero spontaneous magnetization. Many experimental signatures CAF - such as giant thermoelectric Nernst effects should be enhanced when two or more bands are nearly degenerate in vicinity the Fermi energy. Here, we report a zero-field, effect >1 μV/K CoNb3S6 its tiny net magnetization ~2 milli − μB. As drivers...
To improve flash memory retention characteristics, we study detrap current due to oxide traps in metal-oxide-semiconductor structures (MOS capacitors and MOSFETs). We show that threshold voltage shift memories can reach 0.6 V for 1 year. This value is detrimental retention. Next, analyze the two types of conduction mechanism current, which are direct tunneling anode from deeper thermally excited electron band shallower traps. The generated by injection during Fowler-Nordheim stressing, while...
To investigate the origin of DRAM variable retention time (VRT), we use test structures and carefully measure dependence leakage current in DRAM. Consequently find for first that junction fluctuates just like random telegraph signal. We analyze fluctuation detail it VRT
The impact of electron correlation on the Dirac semimetal state is investigated for perovskite CaIrO_{3} in terms magnetotransport properties under varying pressures. reduction with a pressure 1 GPa enhances Fermi velocity as much 40%, but it reduces mobility by an order magnitude detuning node from energy. Moreover, giant magnetoresistance at quantum limit due to one-dimensional confinement electrons critically suppressed pressure. These results indicate that crucial knob controlling...
Random telegraph signals (RTS) in fluctuations of threshold voltage are analyzed using massive readout data scaled flash memories. A novel quantitative analytical method is proposed to evaluate parameters the RTS, such as amplitudes and mean time spent individual states. This evaluation gives us a statistical view RTS well their correlations. All were found follow log-normal distribution show weak mutual dependences. Possible origins distributions discussed. We also studied evolution during...
With the aim of improving flash-memory retention characteristics, we investigated threshold voltage shift (/spl Delta/V/sub th/) due to charge detrapping from tunnel oxide. Accordingly, propose a new parameter that can reveal main origin (hole/electron) and detrap centroid. We found changes holes electrons depending on degree tunnel-oxide degradation. Since hole increases V/sub th/ programmed memory cell, this increase must be considered, especially when designing multi-level flash memory.
Abstract The interplay between electron correlation and topology of relativistic electrons may lead to a fascinating stage the research on quantum materials emergent functions. emergence various collective electronic orderings/liquids, which are tunable by external stimuli, is remarkable feature correlated systems, but has rarely been realized in topological semimetals with high-mobility electrons. Here, we report that Dirac perovskite CaIrO 3 show unconventional field-induced successive...
The electronic structure of compensated antiferromagnets (CAF) has drawn attention for its ability to create large responses, reminiscent ferromagnets and suitable data storage readout, despite (nearly) net-zero spontaneous magnetization. Many the striking experimental signatures predicted CAF, such as giant thermoelectric Nernst effects, are enhanced when two or more bands nearly degenerate in vicinity Fermi energy. Here, we use electric transport experiments study layered, chiral metal...
The thermoelectric Nernst effect of solids converts heat flow to beneficial electronic voltages. Here, using a correlated topological semimetal with high carrier mobility <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>μ</a:mi></a:math> in the presence magnetic fluctuations, we demonstrate an enhancement close phase transition. A instability NdAlSi modifies relaxation time on “hot spots” momentum space, causing strong band filling dependence <c:math...
The dynamic fluctuation of stress-induced leakage current, called V-SILC, which is one the causes erratic bits in flash memory, was investigated. effect V-SILC on memory retention increases with scaling down device dimensions because amplitude constant and does not depend gate area. A statistical analysis indicated that random telegraph noise (RTN) SILC associated state transition a single defect oxide. caused by an electron collision defect.
An anomalous decrease in electron-storage capability of metal-oxide-nitride-oxide-silicon (MONOS) was observed the range nitride thickness below 4 nm. This can be explained by assuming transition layers with electron traps at oxide/nitride interfaces or inhomogeneous growth early stage growth. To a MONOS memory nm for lower power operation and further device scaling down, layer should thinned, roughness reduced.
We have investigated the charge dynamics of correlated Dirac semimetallic perovskite ${\mathrm{CaIrO}}_{3}$ by infrared spectroscopy. The optical conductivity spectra show $\ensuremath{\omega}$-linear-type interband transition and a tiny Drude response at low temperatures, suggesting that node is pinned near Fermi energy due to Mott criticality. Moreover, large polaron absorption appears around 0.04 eV, when thermally excited carriers diminish plasma frequency decreases below phonon energy....
In advanced flash-EEPROM devices, the retention time is limited by "moving bit" (MB), "fast or "anomalous cells", which exhibit anomalously large threshold-voltage shift (/spl Delta/V/sub T/). Since MB caused anomalous charge loss through tunnel oxide, characterization of stress-induced leakage current (SILC) in suitable metal-oxide-semiconductor (MOS) capacitor test structures should be useful for determining responsible mechanism. SILC too small to measure a commercial flash memory cell,...
A new method for predicting the distribution of retention time a dynamic random access memory (DRAM) by using test element group (TEG) has been developed. The TEG is constructed cells which are connected in parallel, so that sum memory-cell leakage currents can be measured. We verified t/sub ret/ main statistically predicted from current. Furthermore, we determined measurement condition detecting some TEGs contain anomalously leaky cells, limit DRAM refreshing interval.
A decrease in breakdown voltage (VBD) the termination area of 4H-SiC PN diodes after 64 h reverse-bias stressing was analyzed. To analyze VBD decrease, a novel analysis method based on results measuring depletion-layer capacitance proposed. The measurement indicate that positive-charge density (QTM) at SiO2/SiC interface increased stressing. Besides, case QTM 1012 cm−2 interface, measured showed same tendency as simulated capacitance. By comparing full depletion and voltage, amount...
We build a method for measuring leakage current of anomalously leaky cells (tail cells) in dynamic random access memories. find that the traps tail are at region stronger electric field p-n junction and their energy levels nearer midgap than respective values average cells.
We investigated gate oxide degradation to focus on two topics, which were neutral trap generation and stress-induced leakage current (SILC). show that the traps generated by hole injection during Fowler-Nordheim stressing. The experimental result shows existence of precursor. also relationship between density SILC was linear in 6.2 nm thick deviation from linearity observed thicker oxide. suggests cause same mechanism. Meanwhile, change conduction mechanism SILC, is, single multiple...
We report an observation of Weyl fermions in momentum space itinerant ferromagnet SrRuO3 single crystal via inelastic optical spectroscopy. A clear magnetic resonance around 200 GHz is observed the Brillouin light scattering spectra, which corresponds to ferromagnetic at Γ point. The spin-wave gap shows non-monotonous temperature dependence distinct from bulk magnetization. peculiar evolution scales with that anomalous Hall conductivity, a hallmark near Fermi energy.
The thermoelectric Nernst effect of solids converts heat flow to beneficial electronic voltages. Here, using a correlated topological semimetal with high carrier mobility $\mu$ in presence magnetic fluctuations, we demonstrate an enhancement the close phase transition. A instability NdAlSi modifies relaxation time on 'hotspots' momentum space, causing strong band filling dependence $\mu$. We quantitatively derive parameters from novel two-band analysis $S_{xy}$, good agreement quantum...
Abstract Noncoplanar magnets are excellent candidates for spintronics. Particularly important those with clear electrical transport signatures that can simplify data readout – however, such materials difficult to find, and even more so intentionally design. Here, we report a chemical design strategy allowed us find series of new non-coplanar Ln3Sn7 (Ln = Dy, Tb), by targeting layered take decoupled magnetic sublattices dissimilar single-ion anisotropies, combining square-net topological...
Noncoplanar magnets are excellent candidates for spintronics. However, such materials difficult to find, and even more so intentionally design. Here, we report a chemical design strategy that allows us find series of noncoplanar magnets—Ln3Sn7 (Ln = Dy, Tb)—by targeting layered have decoupled magnetic sublattices with dissimilar single-ion anisotropies combining those square-net topological semimetal sublattice. Ln3Sn7 shows high carrier mobilities upwards 17,000 cm2 ⋅ V−1 s−1, hosts order....