Minoru Osada

Two-dimensional (2D) nanosheets, which possess atomic or molecular thickness and infinite planar lengths, are regarded as the thinnest functional nanomaterials. The recent development of methods for manipulating graphene (carbon nanosheet) has provided new possibilities and applications for 2D systems; many amazing functionalities such as high electron mobility and quantum Hall effects have been discovered. However, graphene is a conductor, and electronic technology also requires insulators, whi

Two-dimensional (2D) nanosheets obtained via exfoliation of layered compounds have attracted intense research in recent years. In particular, the development of exotic 2D systems such as stable graphene and transition-metal oxide nanosheets has sparked new discoveries in condensed matter physics and nanoelectronics. Here, we review the progress made in the synthesis, characterization and properties of oxide nanosheets, highlighting emerging functionalities in electronic and spin-electronic appli

2D titania nanosheets are attractive candidates as insulating materials for high-κ dielectrics. Solution-based layer-by-layer deposition combined with an atomically flat SrRuO3 electrode produces atomically uniform multilayer nanofilms. These nanofilms exhibit high relative dielectric constants (ϵr) of approximately 125, even for thicknesses down to 10 nm, in contrast to size- induced degradation typical in high-κ materials (see figure).

Raman spectra of Bi 4- x La x Ti 3 O 12 have been investigated. For an increasing degree of La doping, we find a substantial hardening of the vibration involving Bi atoms at the perovskite A site, whereas the Bi mode at the Bi 2 O 2 layer is negligibly changed. From a comparison with a simple mass consideration, we identify a precise cation distribution, which indicates a pronounced site selectivity of La ions for the A site for x <∼ 1. At room temperature, the lowest mode at 28 cm -1 shows a

Size-induced suppression of permittivity in perovskite thin films is a fundamental problem that has remained unresolved for decades. This size-effect issue becomes increasingly important due to the integration of perovskite nanofilms into high-κ capacitors, as well as concerns that intrinsic size effects may limit their device performance. Here, we report a new approach to produce robust high-κ nanodielectrics using perovskite nanosheet (Ca2Nb3O10), a new class of nanomaterials that is derived f

A two-dimensional titania nanosheet is proven to be useful as a host for spinelectronic materials. Magneto–optical measurements demonstrate that Co-substituted titania nanosheets (Ti0.8Co0.2O2) act as nanoscale ferromagnetic layers at room temperature, and their multilayer assemblies exhibit robust magnetic circular dichroism (MCD) in the ultraviolet–visible region. The availability of ferromagnetic nanostructures allows the rational design of high-efficiency magneto–optical devices.

Vapor transportation is the core process in growing transition-metal dichalcogenides (TMDCs) by chemical vapor deposition (CVD). One inevitable problem is the spatial inhomogeneity of vapors. The non-stoichiometric supply of transition-metal precursors and chalcogens leads to poor control in the products' location, morphology, crystallinity, uniformity and batch to batch reproducibility. The vapor-liquid-solid (VLS) growth method often involves molten precursors (e.g., non-volatile Na2MoO4) at g

We have investigated magnetic and magneto-optical properties of two-dimensional (2D) ${\mathrm{Ti}}_{0.8}{\mathrm{Co}}_{0.2}{\mathrm{O}}_{2}$ nanosheet, a new nanosized titanium oxide derived from layered titanates by exfoliation. Despite heavy doped 2D system in the dielectric ground, the multilayer films of ${\mathrm{Ti}}_{0.8}{\mathrm{Co}}_{0.2}{\mathrm{O}}_{2}$ nanosheets exhibit room-temperature ferromagnetism with magnetic moment of $1.4{\ensuremath{\mu}}_{B}∕\mathrm{Co}$. We also observe

Ultrathin films with high-k dielectric/ferroelectric properties form the basis of modern electronics. With further miniaturization of electronic devices, conventional materials are expected to experience a challenge because of their critical thickness, where the dielectric/ferroelectric responses are unstable or even disappeared if the film thickness is reduced to the nanometer scale or below a two-dimensional (2D) limit. Owing to the benefit of preparing stable atomically thin film, 2D material

Abstract An important challenge in current microelectronics research is the development of techniques for making smaller, higher‐performance electronic components. In this context, the fabrication and integration of ultrathin high‐ κ dielectrics with good insulating properties is an important issue. Here, we report on a rational approach to produce high‐performance nanodielectrics using one‐nanometer‐thick oxide nanosheets as a building block. In titano niobate nanosheets (TiNbO 5 , Ti 2 NbO 7 ,

Abstract A novel atomic stacking transporting layer (ASTL) based on 2D atomic sheets of titania (Ti 1− δ O 2 ) is demonstrated in organic–inorganic lead halide perovskite solar cells. The atomically thin ASTL of 2D titania, which is fabricated using a solution‐processed self‐assembly atomic layer‐by‐layer deposition technique, exhibits the unique features of high UV transparency and negligible (or very low) oxygen vacancies, making it a promising electron transporting material in the development