arXiv subjects

Takahiro Ono

Publications and source records attributed to Takahiro Ono.

3 recordsLinked to original sources

arXiv2026

Individual Characterization of Fast-Responding Trap States at the NO-Annealed SiO$_2$/4H-SiC Interface

Fast-responding trap states introduced by NO-annealing are suspected to limit the channel mobility of 4H-SiC MOSFETs, yet their microscopic characterization remains challenging because conventional electrical methods are spatially averaged and do not readily isolate such fast processes. Here, we visualize and analyze individual fast-responding trap states at the NO-annealed SiO$_2$/4H-SiC interface using the energy dissipation signal in frequency-modulation atomic force microscopy (FM-AFM), which selectively probes charge-exchange dynamics on sub-$μ$s time scales. Ring-shaped dissipation patterns were observed in the NO-annealed sample but not in the control sample without NO-annealing, indicating that the detected states are associated with nitridation. Spectroscopic measurements were also performed to determine the dependence of energy dissipation on the tip bias and the tip-sample distance. Combined with finite-element electrostatic calculations, this analysis allowed us to determine trap energies relative to the Fermi level, $E_t - E_f$, and revealed that the trap-energy distribution extends toward the interfacial conduction-band edge. These results provide microscopic evidence that NO-annealing generates fast-responding trap states near the SiO$_2$/4H-SiC interface.

cond-mat.mtrl-sci↗

arXiv2023

Growth of self-integrated atomic quantum wires and junctions of a Mott semiconductor

Continued advances in quantum technologies rely on producing nanometer-scale wires. Although several state-of-the-art nanolithographic technologies and bottom-up synthesis processes have been used to engineer such wires, critical challenges remain in growing uniform atomic-scale crystalline wires and constructing their network structures. Here we discover a simple method to fabricate atomic-scale wires with various arrangements, including stripes, X-, Y-junctions, and nanorings. Single-crystalline atomic-scale wires of a Mott insulator, whose band gap is comparable to those of wide-gap semiconductors, are spontaneously grown on graphite substrates \DEL{and epitaxial monolayer graphene on SiC }by pulsed-laser deposition. These wires are one-unit-cell-thick and have an exact width of two- and four-unit-cells (1.4 and 2.8\,nm) and lengths up to a few $μm$. We show that the non-equilibrium reaction-diffusion processes may play an essential role in atomic pattern formation. Our findings offer a new perspective on the non-equilibrium self-organization phenomena on an atomic scale, paving a unique way for the quantum architecture of nano-network.

cond-mat.mes-hall↗

arXiv2021

Predual of weak Orlicz spaces

In this paper, we consider the predual spaces of weak Orlicz spaces. As an application, we provide the Fefferman-Stein vector-valued maximal inequality for the weak Orlicz spaces. In order to prove this statement, we introduced the Orlicz-Lorentz spaces, and showed the boundedness of the Hardy-Littlewood maximal operator on these spaces.

math.FA↗