Preparation of Au/ZnO nanocomposites by radio frequency co-sputtering

Au/ZnO nanocomposite films were prepared by co-sputtering of ZnO and gold wires. The composite films were transparent and red in color due to surface plasmon resonance absorption of small Au particles. The composite films were annealed at different temperatures in argon atmosphere to study the evolution of the size of Au particles and subsequent change in their optical properties. With the increase of annealing temperature, the size of the Au particles increased and the intensity of plasmon resonance absorption peak increased.     

Controlled Polarizability of One‐Nanometer‐Thick Oxide Nanosheets for Tailored,High‐κ Nanodielectrics

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 (TiNbO₅, Ti₂NbO₇, Ti₅NbO₁₄), the octahedral distortion inherent to site‐engineering by Nb incorporation results in a giant molecular polarizability, and their multilayer nanofilms exhibit a high dielectric constant (160–320), the largest value seen so far in high‐κ nanofilms with thickness down to 10 nm. Furthermore, these superior high‐κ properties are fairly temperature‐independent with low leakage‐current density (<10^?7 A cm^?2). This work may provide a new recipe for designing nanodielectrics desirable for practical high‐κ devices.     

A DIL-type miniature optical transceiver module using an InGaAsPhalf-transmittance photodiode for TCM optical access networks

A compact DIL-type miniature optical transceiver module has been developed without using a conventional 3 dB optical coupler. This transceiver is composed of a newly designed InGaAsP half-transmittance photodiode (HT-PD) and a 1.3-μm multiquantum-well laser diode (MQW-LD). An HT-PD is used both as a photodetector and as a window for laser diode (LD) light. Fiber output power of 0 dBm at the drive current of 33.8 mA and responsivity of 0.58 A/W at the reverse-voltage of 2 V were obtained. The fundamental characteristics of the HT-PD are studied and discussed     

Direct analysis method for probabilistic fracture mechanics

A new method for solving problems of probabilistic fracture mechanics (PFM) is proposed. A process of crack growth is reduced into an iterative integration equation with respect to the probabilistic distribution functions of crack geometry using approximate independence, which we have introduced. The integration equation which has a form of Stieltjes integral is solved by a numerical method. Some PFM problems are solved using the present method, and the results are compared with those by the MC method. Failure probabilities obtained from both calculations agree well. Execution time of the present method is shown to be remarkably short.     

Exploring MARS: developing indoor and outdoor user interfaces to a mobile augmented reality system

We describe an experimental mobile augmented reality system (MARS) testbed that employs different user interfaces to allow outdoor and indoor users to access and manage information that is spatially registered with the real world. Outdoor users can experience spatialized multimedia presentations that are presented on a head-tracked, see-through, head-worn display used in conjunction with a hand-held pen-based computer. Indoor users can get an overview of the outdoor scene and communicate with outdoor users through a desktop user interface or a head- and hand-tracked immersive augmented reality user interface.     

Local lattice parameter determination of a silicon (001) layer grown on a sapphire (1102) substrate using convergent-beam electron diffraction

All the six lattice parameters (a, b, c, alpha, beta and gamma) of a Si (001) layer grown on a sapphire (1102) substrate were determined by convergent-beam electron diffraction with no assumption of crystal lattice symmetry. A lattice compression in the Si (001) plane and an elongation in the [001] direction were revealed. An anisotropic lattice compression in the (001) plane was clearly detected for the first time. That is, the lattice compression in the Si [100] direction, which is parallel to the sapphire [1101] direction, was larger than that of the Si [010] direction, which is parallel to the sapphire [1120] direction. It was also revealed that the lattice parameters of the Si-layer depend on the distance from the interface. Anisotropy of carrier mobility was reasonably explained in terms of the anisotropy of the lattice parameters determined.     

A possible buckybowl-like structure of zeolite templated carbon

Ordered microporous carbon that was synthesized in the nanochannels of zeolite Y is characterized by an extremely large surface area, surprisingly uniform micropores and a long-range periodicity originating from the parent zeolite. However, the molecular structure of this zeolite templated carbon (ZTC) has been completely unknown. In this study, an attempt was made to construct a possible molecular model for ZTC. The proposed model is made up of buckybowl-like nanographenes assembled into a three-dimensionally regular network, which reflects all the experimental results obtained from Raman spectroscopy, electron energy-loss spectroscopy, and previously obtained analyses with several other means. Starting from this idealized model, possible forms of defects that would be included in the actual ZTC were also investigated. Moreover, the amount and the type of oxygen functional groups were analyzed and, as per the results, some functional groups were bound to the edge sites of each buckybowl unit in the molecular model. The elemental composition, pore curvature, pore size and pore volume and surface area estimated from such oxygen-containing model agree well with the corresponding experimentally obtained results. The present model can be considered as a reasonable starting point for future refinements of the structure of this quite novel carbon material.     

Structures and Polymorphic Transitions of Triacylglycerols, SOS and POS Thin Films: A Study on Temperature Dependence

X-ray reflectivity (XR) and scanning probe microscopy (SPM) were used to examine the structures, polymorphic transitions, and surface morphologies of triacylglycerol (TAG), 1,3-stearin-2-olein (SOS) and 1-palmitin-2-olein-3-stearin (POS) thin films supported on Si substrates. The structural parameters: thickness, electron density, and surface/interface roughnesses of TAG thin films were determined by the nonlinear least-squares regression of XR profiles to reveal their temperature dependences. In the lower temperature regimes, we observed Bragg peaks without significant interference fringe patterns in the XR profiles. SPM at room temperature displayed isolated islands on TAG thin films with surface undulations. Whereas in the higher temperature regimes in which the Bragg peaks disappeared, the interference fringe patterns became prominent. The analyses of the XR profiles indicated the structural change in thin films from three layers to single layer on Si substrates with increasing temperature. However, the temperatures at which the structural change occurred were obviously different between SOS and POS thin films.     

Postsynthesis of h‐BN/Graphene Heterostructures Inside a STEM

Combinations of 2D materials with different physical properties can form heterostructures with modified electrical, mechanical, magnetic, and optical properties. The direct observation of a lateral heterostructure synthesis is reported by epitaxial in‐plane graphene growth from the step‐edge of hexagonal BN (h‐BN) within a scanning transmission electron microscope chamber. Residual hydrocarbon in the chamber is the carbon source. The growth interface between h‐BN and graphene is atomically identified as largely N–C bonds. This postgrowth method can form graphene nanoribbons connecting two h‐BN domains with different twisting angles, as well as isolated carbon islands with arbitrary shapes embedded in the h‐BN layer. The electronic properties of the vertically stacked h‐BN/graphene heterostructures are investigated by electron energy‐loss spectroscopy (EELS). Low‐loss EELS analysis of the dielectric response suggests a robust coupling effect between the graphene and h‐BN layers.