Wafer-Scale Epitaxial Growth of an Atomically Thin Single-Crystal Insulator as a Substrate of Two-Dimensional Material Field-Effect Transistors.

As the electron mobility of two-dimensional (2D) materials is dependent on an insulating substrate, the nonuniform surface charge and morphology of silicon dioxide (SiO) layers degrade the electron mobility of 2D materials. Here, we demonstrate that an atomically thin single-crystal insulating layer of silicon oxynitride (SiON) can be grown epitaxially on a SiC wafer at a wafer scale and find that the electron mobility of graphene field-effect transistors on the SiON layer is 1.5 times higher than that of graphene field-effect transistors on typical SiO films.

Ultrafast Unbalanced Electron Distributions in Quasicrystalline 30° Twisted Bilayer Graphene.

Ultrafast carrier dynamics in a graphene system are very important in terms of optoelectronic devices. Recently, a twisted bilayer graphene has been discovered that possesses interesting electronic properties owing to strong modifications in interlayer couplings. Thus, a better understanding of ultrafast carrier dynamics in a twisted bilayer graphene is highly desired.

Millimeter-Scale Growth of Single-Oriented Graphene on a Palladium Silicide Amorphous Film.

It is widely accepted in condensed matter physics and material science communities that a single-oriented overlayer cannot be grown on an amorphous substrate because the disordered substrate randomizes the orientation of the seeds, leading to polycrystalline grains. In the case of two-dimensional materials such as graphene, the large-scale growth of single-oriented materials on an amorphous substrate has remained unsolved. Here, we demonstrate experimentally that the presence of uniformly oriented graphene seeds facilitates the growth of millimeter-scale single-oriented graphene with 3 × 4 mm on palladium silicide, which is an amorphous thin film, where the uniformly oriented graphene seeds were epitaxially grown.

Dirac electrons in a dodecagonal graphene quasicrystal.

Quantum states of quasiparticles in solids are dictated by symmetry. We have experimentally demonstrated quantum states of Dirac electrons in a two-dimensional quasicrystal without translational symmetry. A dodecagonal quasicrystalline order was realized by epitaxial growth of twisted bilayer graphene rotated exactly 30°.

Seamless lamination of a concave-convex architecture with single-layer graphene.

Graphene has been used as an electrode and channel material in electronic devices because of its superior physical properties. Recently, electronic devices have changed from a planar to a complicated three-dimensional (3D) geometry to overcome the limitations of planar devices. The evolution of electronic devices requires that graphene be adaptable to a 3D substrate.

Epitaxial growth of a single-crystal hybridized boron nitride and graphene layer on a wide-band gap semiconductor.

Vertical and lateral heterogeneous structures of two-dimensional (2D) materials have paved the way for pioneering studies on the physics and applications of 2D materials. A hybridized hexagonal boron nitride (h-BN) and graphene lateral structure, a heterogeneous 2D structure, has been fabricated on single-crystal metals or metal foils by chemical vapor deposition (CVD). However, once fabricated on metals, the h-BN/graphene lateral structures require an additional transfer process for device applications, as reported for CVD graphene grown on metal foils.

Direct momentum-resolved observation of one-dimensional confinement of externally doped electrons within a single subnanometer-scale wire.

Cutting-edge research in the band engineering of nanowires at the ultimate fine scale is related to the minimum scale of nanowire-based devices. The fundamental issue at the subnanometer scale is whether angle-resolved photoemission spectroscopy (ARPES) can be used to directly measure the momentum-resolved electronic structure of a single wire because of the difficulty associated with assembling single wire into an ordered array for such measurements. Here, we demonstrated that the one-dimensional (1D) confinement of electrons, which are transferred from external dopants, within a single subnanometer-scale wire (subnanowire) could be directly measured using ARPES.

Designed three-dimensional freestanding single-crystal carbon architectures.

Single-crystal carbon nanomaterials have led to great advances in nanotechnology. The first single-crystal carbon nanomaterial, fullerene, was fabricated in a zero-dimensional form. One-dimensional carbon nanotubes and two-dimensional graphene have since followed and continue to provide further impetus to this field.

Alterations of contractions and L-type Ca2+ currents by murrayafoline-A in rat ventricular myocytes.

We examined the effects of murrayafoline-A (1-methoxy-3-methylcarbazole, Mu-A), which is isolated from the dried roots of Glycosmis stenocarpa, on cell shortenings and L-type Ca2+ currents (ICa,L) in rat ventricular myocytes. Cell shortenings and ICa,L were measured using the video edge detection method and patch-clamp techniques, respectively. Mu-A transiently increased cell shortenings in a concentration-dependent manner with an EC50 of ~20 μM.

Wafer-scale growth of single-crystal monolayer graphene on reusable hydrogen-terminated germanium.

The uniform growth of single-crystal graphene over wafer-scale areas remains a challenge in the commercial-level manufacturability of various electronic, photonic, mechanical, and other devices based on graphene. Here, we describe wafer-scale growth of wrinkle-free single-crystal monolayer graphene on silicon wafer using a hydrogen-terminated germanium buffer layer. The anisotropic twofold symmetry of the germanium (110) surface allowed unidirectional alignment of multiple seeds, which were merged to uniform single-crystal graphene with predefined orientation.

Opening and reversible control of a wide energy gap in uniform monolayer graphene.

For graphene to be used in semiconductor applications, a 'wide energy gap' of at least 0.5 eV at the Dirac energy must be opened without the introduction of atomic defects. However, such a wide energy gap has not been realized in graphene, except in the cases of narrow, chemically terminated graphene nanostructures with inevitable edge defects.

Focused-laser-enabled p-n junctions in graphene field-effect transistors.

With its electrical carrier type as well as carrier densities highly sensitive to light, graphene is potentially an ideal candidate for many optoelectronic applications. Beyond the direct light-graphene interactions, indirect effects arising from induced charge traps underneath the photoactive graphene arising from light-substrate interactions must be better understood and harnessed. Here, we study the local doping effect in graphene using focused-laser irradiation, which governs the trapping and ejecting behavior of the charge trap sites in the gate oxide.

An organometallic approach for ultrathin SnO(x)Fe(y)S(z) plates and their graphene composites as stable anode materials for high performance lithium ion batteries.

Through an organometallic approach, ultrathin SnO(x)Fe(y)S(z) plates with ~2 nm single layer-thicknesses were obtained and their graphene composites showed very promising discharge capacities of up to 736 mA h g(-1) and excellent stabilities as anode materials in lithium ion batteries.

Atrial local Ca2+ signaling and inositol 1,4,5-trisphosphate receptors.

In atrial myocytes lacking t-tubules, action potential triggers junctional Ca(2+) releases in the cell periphery, which propagates into the cell interior. The present article describes growing evidence on atrial local Ca(2+) signaling and on the functions of inositol 1,4,5-trisphosphate receptors (IP(3)Rs) in atrial myocytes, and show our new findings on the role of IP(3)R subtype in the regulation of spontaneous focal Ca(2+) releases in the compartmentalized areas of atrial myocytes. The Ca(2+) sparks, representing focal Ca(2+) releases from the sarcoplasmic reticulum (SR) through the ryanodine receptor (RyR) clusters, occur most frequently at the peripheral junctions in isolated resting atrial cells.

Inhibition of L-type Ca2+ channel by mitochondrial Na+-Ca2+ exchange inhibitor CGP-37157 in rat atrial myocytes.

7-chloro-5-(2-chlorophenyl)-1,5-dihydro-4,1-benzothiazepine-2(3H)-one (CGP-37157) inhibits mitochondrial Na(+)-Ca(2+) exchange. It is often used as an experimental tool for studying the role of the mitochondrial Na(+)-Ca(2+) exchanger in Ca(2+) signaling. Because the selectivity of CGP-37157 in adult cardiomyocytes has not been confirmed, we tested whether CGP-37157 affects the L-type Ca(2+) channel using a whole-cell patch-clamp in adult rat atrial myocytes.

Cycloaddition reaction of 1,3-butadiene with a symmetric Si adatom pair on the Si(111)7x7 surface.

We first found experimentally a cycloaddition reaction of a molecule on a symmetry Si pair, 1,3-butadiene on the Si adatom pair of Si(111)7x7, while up to now only asymmetric Si pairs were reported to be involved in cycloaddition reactions on Si surfaces. As the symmetry of a Si pair is expected to influence significantly a cycloaddition product and a reaction pathway, the [4+2]-like cycloaddition product of 1,3-butadiene on the Si adatom pair is suggested to form through a concerted reaction pathway in comparison to a stepwise reaction pathway, which is favorable in the formation of the [4+2]-like cycloaddition product on the asymmetric Si pair (the Si adatom-restatom pair).