Ge surfaces were irradiated by Ar⁺ ions at 600eV with and without simultaneous supply of Ge or Al at room temperature. The surfaces ion-irradiated without any simultaneous metal supply were characterized by densely distributed conical protrusions. By contrast, various kinds of nanostructures were formed on the Ge surfaces ion-irradiated with a simultaneous metal supply. They featured cones and nanobelts with a flattened top for Ge supply cases, whereas they were characterized by the nanorods, nanobelts and nanowalls for Al supply cases. Very interestingly, most of the nanorods and nanobelts formed with an Al supply possessed a bottleneck structure. Thus, the Ge nanostructures were controllable in morphology by species and amount of simultaneously supplied metals.

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Alumina supported cobalt-ferrum catalysts were prepared using wet impregnation method by applying 3 different conditions, namely hotplate (A), sonication (B) and soaking (C). The alumina supported cobalt-ferrum catalysts were applied in the synthesis of multi-walled carbon nanotubes (MWNTs) using catalytic chemical vapour deposition (CCVD) technique. The morphology and particle size of the cobalt-ferrum catalysts and the MWNTs yield were examined by field emission-scanning electron microscopy (FE-SEM) while the surface elemental composition of the samples was obtained by energy dispersive X-ray analysis (EDX). The morphology of catalysts A, B and C were found to be different, the particle sizes were ranged from 20-40 nm. The diameters of the MWNTs yield from samples A, B and C were found to be related to the catalyst particle size, thus the smaller the catalyst particle, the thinner the MWNTs obtained. The MWNTs with smaller diameter were obtained with higher purity and quality becuase the nanotube surface are free from amorphous carbon. Therefore, different catalyst preparation methods resulted in different sizes of the catalyst particle in order to synthesize MWNTs with desired diameter.

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Carbon nanotubes (CNTs) have generated great interest within the many areas of nanotechnology due to their superior and outstanding physical properties. However effective dispersion in many solvents has imposed limitations upon the use of CNTs in a number of novel applications. Functionalization presents a solution for CNTs to be more soluble which make them integrate well into any organic, inorganic or biological systems. CNTs can be easily functionalized using cyclodextrin (CD) treatment. The CD modification of carbon nanotubes is both simple and effective. It requires no prolonged heating, filtration and washing which can severely damage the small diameter nanotubes. The formation of surface functional groups and changes of nanotubes structures of functionalized carbon nanotubes (f-CNTs) were monitored by Fourier transform infrared spectroscopy (FTIR), Thermo gravimetric analysis (TGA) and field emission scanning electron microscopy (FESEM), respectively. From the TGA results, the amount of weight loss of the f-CNTs in varying ratios indicated the amount of CD that was functionalized. It was also noted that the FTIR spectra showed the presence of functional groups associated with CD in the f-CNTs. As a result, the cyclodextrin groups were found to be possibly adsorbed at the surface of the nanotubes walls. The f-CNTs showed substantial solubility in N-methyl-2-pyrrolidone (NMP) which helps in a better distribution of the CNTs in the mixed matrix membrane (MMM) prepared. Hence, the influence of the f-CNTs in the polymer matrix will give rise to enhanced physical properties of the MMM suitable for applications in gas separations.

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We report the growth of carbon nanofibers (CNFs) from carbon particles by chemical vapor deposition (CVD) with ultrasonic neblizer using ethanol as carbon source. Dense CNFs having diameters of several tens of nanometers have been successfully synthesized by the CVD without using any metal catalysts. The carbon particles formed from decompostion of fullerene were found to be suitable for the synthesis of CNFs. Details of the optimum conditions for producing CNFs and the expected growth mechanism are also described.

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Al doped zinc oxide (AZO) films were deposited using a radio frequency (rf) magnetron sputtering apparatus with a mesh grid electrode. Improvement of crystalline uniformity was achieved by the use of an appropriate negative grid bias to effectively suppress the bombardment of high-energy charged particles onto the film surface. The uniformity of the film's electronic properties, such as resistivity, carrier concentration and Hall mobility, was also improved using the sputtering method. Hydrogen plasma annealing was investigated to further decrease the resistivity of the ZnO films and the carrier concentration was increased by 1-2×10²⁰cm^-3 without decrease in the Hall mobility.

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Initial growth of GaP on Si substrates using metalorganic vapor phase epitaxy was studied. Si substrates were exposed to PH₃ preflow for 15s or 120s at 830°C after they were preheated at 925°C. Atomic force microscopy (AFM) revealed that the Si surface after preflow for 120s was much rougher than that after preflow for 15s. After 1.5nm GaP deposition on the Si substrates at 830°C, GaP islands nucleated more uniformly on the Si substrate after preflow for 15s than on the substrate after preflow for 120s. After 3nm GaP deposition, layer structures were observed on a fraction of Si surface after preflow for 15s. Island-like structures remained on the Si surface after preflow for 120s. After 6nm GaP deposition, the continuity of GaP layers improved on both substrates. However, AFM shows pits that penetrated a Si substrate with preflow for 120s. Transmission electron microscopy of a GaP layer on the Si substrate after preflow for 120s revealed that V-shaped pits penetrated the Si substrate. The preflow for a long time roughened the Si surface, which facilitated the pit formation during GaP growth in addition to degrading the surface morphology of GaP at the initial growth stage. Even after 50nm GaP deposition, pits with a density on the order of 10⁷cm^-2 remained in the sample. A 50-nm-thick flat GaP surface without pits was achieved for the sample with PH₃ preflow for 15s. The PH₃ short preflow is necessary to produce a flat GaP surface on a Si substrate.

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Carbon nanofibers (CNFs) were fabricated on graphite plates using “Ar⁺ ion sputtering method” in large amount at room temperature. The morphology of CNFs was controlled by a simultaneous carbon supply during ion sputtering. CNF-tipped cones were formed on graphite plate surfaces without carbon supply whereas those with a simultaneous carbon supply featured mainly needle-like protrusions of large size. The field electron emission (FE) properties, measured using parallel plate configurations in 10^-4 Pa range, showed the threshold fields of 4.4 and 5.2V/µm with a current density of 1 µA/cm² for CNF-tipped cones and needle-like protrusion, respectively. Reliability test results indicated that CNF-tipped cones were more stable than needle-like protrusion. The morphological change after reliability test showed a so-called “self-regenerative” process and structure damage for CNF-tipped cones and needle-like protrusions, respectively.

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We report Ultraviolet (UV)-induced visible light luminescence in artificial-lattice thin films of ion-doped silica glass (silica superstructure thin films). The film was composed of periodic nanometer layers of germanium-doped silica (Ge: SiO₂), titanium-doped silica (Ti: SiO₂), and tin-doped silica (Sn: SiO₂). The thickness of each layer was between 10 and 30nm. Despite the small thickness of the film (few microns), a relatively bright luminescence of white light was observed, along with cathode-ray luminescence in the superstructure film. In addition, irradiation of the superstructure film with UV light led to light amplification by stimulated emission at 405nm. The experimental results suggest the potential application of silica superstructure thin films as optical amplifiers.

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The idea of using molecules and molecular structures as functional electronic device, promises to substantially decrease the size and improve the performance of electronic devices. In this paper, nonequilibrium Green's function formalism (NEGF) combined with extended Huckel theory (EHT), a semiempirical approach is used to study the electron transport phenomenon in single molecular junction systems. Benzene diamine molecule is studied to investigate the bonding of amine group to gold electrodes and the electron transport across the junction. The results are compared with that of benzene dithiol molecule with thiol end groups. Furthermore, the influence of charging and torsion angle on the transport characteristics is emphasized.

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Indium-sulfide-oxide thin films have been successfully deposited on indium-tin-oxide-coated glass from an aqueous solution containing Na₂S₂O₃ and In₂(SO₄)₃ by electrochemical deposition using a periodic 2-step-pulse voltage. The films have been annealed in nitrogen atmosphere for an hour at different temperatures; namely, 100, 200, 300 and 400°C. Then, the as-deposited and annealed films were characterized structurally, morphologically and optically. X-ray photoelectron spectroscopy (XPS) study was performed in order to understand the chemical states of the oxygen involved in the film composition. The photosensitivity was observed by means of photoelectrochemical measurements, which confirmed that the as-deposited and annealed films showed n-type conduction. Moreover, a heterostructure solar cell that has indium sulfide as a buffer layer and tin sulfide as an absorber was fabricated and characterized.

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Interface state density was estimated from diode factor n of SiC MIS Schottky diode. The interface state density was the order of 10¹²cm^-2eV^-1, and was same order to the value for the sample carefully prepared by oxidation and post oxidation annealing. The interface state density determined from n was consistent to the value calculated from the capacitance voltage curve of SiO₂/nitride/SiC MIS diode by Terman method. High temperature nitridation was effective to reduce the interface state density.

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Electrical characteristics of P3HT/Aluminum organic/inorganic heterojunction diodes were investigated V-I and capacitance-voltage (C-V) measurements. The V-I measurement exhibited current rectification inherent in the Schottky diode, suggesting their availabilities as rectification diodes in organic flexible circuits. C-V analysis indicated the fact that the depletion layer was generated in the P3HT film in the reversed bias condition. The flat band voltage analysis suggested that the interfacial charge affected the built-in potential of the diodes. Al/P3HT heterojunction is possible to be used as not only the rectification diodes but also gate junctions for junction type field effect or static induction transistors.

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A variety of ZnO belt-like structures were synthesized by the heat treatment of ZnS substrates with Ga droplets in the air, and their morphological and structural properties were investigated. Three types of ZnO belts with flat surfaces of ±(2110), ±(1100) and ±(1213) were obtained. As comparison, the ZnO crystal growth was examined by the thermal oxidation of ZnS only. These results highlight the promise of the heat treatment with Ga in the synthesis of oxide nanostructures.

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The synthesis of single- and double-wall carbon nanotubes by gas flow-modified, catalyst-supported chemical vapor deposition (CCVD) is reported. We have investigated the gas flow condition dependence on the synthesis of carbon nanotubes (CNTs) by placing blocks in the CCVD reactor. Carbon nanotubes having large diameters are preferentially grown under turbulent flow conditions. This indicates that the diameter distribution of CNTs can be controlled by modification of the gas flow condition in the CCVD.

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We investigated an analogue modulation of magneto-optic spatial light modulator (MOSLM). For enhancement of the modulation from the voltage-driving MOSLM, magnetostriction and saturation magnetization of magnetic garnet films and piezoelectric constant of PZT films were investigated. The performance was expected to be improved by using Bismuth, Dysprosium and Aluminum substituted Yttrium Iron garnet, which effective magnetic field showed 20 times higher than Yttrium Iron garnet.

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An improved nonlinear circuit model for a GaAs Gunn diode in an oscillator is proposed based on the physical mechanism of the diode. This model interprets the nonlinear harmonic character on the Gunn diode. Its equivalent nonlinear circuit of which can assist in the design of the Gunn oscillator and help in the analysis of the fundamental and harmonic characteristics of the GaAs Gunn diode. The simulation prediction and the experiment of the Gunn oscillator show the feasibility of the nonlinear circuit model for the GaAs Gunn oscillator.

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This paper presents a wide tuning range VCO with an automatic frequency, gain, and two-step amplitude calibration loop for Digital TV (DTV) tuner applications. To cover the wide tuning range, the fully digital automatic frequency calibration (AFC) loop is used. In addition to the AFC loop, a two-step negative-G_m tuning loop is proposed to provide the optimum negative-G_m to the LC tank in a wide frequency range with a fine resolution. In the coarse negative-G_m tuning loop, the number of active negative-G_m cells is selected digitally based on the target frequency. In the fine negative-G_m tuning loop, the negative-G_m is tuned finely with the bias voltage of the VCO. Also, the digital VCO gain calibration scheme is proposed to compensate for the gain variation in a wide tuning range. The VCO tuning range is 2.6GHz, from 1.7GHz to 4.3GHz, and the power consumption is 2mA to 4mA from a 1.8V supply. The measured VCO phase noise is -120dBc/Hz at 1MHz offset.

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This paper presents a measurement method for determining effective conductivity of copper-clad dielectric laminate substrates in the millimeter-wave region. The conductivity is indirectly evaluated from measured resonant frequencies and unloaded Q values of a number of Whispering Gallery modes excited in a circular disk sample, which consists of a copper-clad dielectric substrate with a large diameter of 20-30 wavelengths. We can, therefore, obtain easily the frequency dependence of the effective conductivity of the sample under test in a wide range of frequency at once. Almost identical conductivity is predicted for two kinds of WG resonators (the copper-clad type and the sandwich type) with different field distribution; it is self-consistent and provides the important foundation for the method if not for the alternative method at this moment. We measure three kinds of copper foils in 55-65GHz band, where the conductivity of electrodeposited copper foil is smaller than that of rolled copper foil and shiny-both-sides copper foil. The measured conductivity for the electrodeposited copper foil decreases with an increase in the frequency. The transmission losses measured for microstrip lines which are fabricated from these substrates are accurately predicted with the conductivity evaluated by this method.

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A three-dimensional semiconductor package structure with inter-chip connections was developed for broadband data transfer and low latency electrical communication between a high-capacity memory and a logic device interconnected by a feedthrough interposer (FTI) featuring a 10µm scale fine-wiring pattern and ultra-fine-pitch through vias. This technology features co-existence of the wide-band memory accessibility of a system-on-chip (SoC) and the capability of memory capacity increasing of a system-in-package (SiP) that is made possible by the individual fabrication of memory and logic on independent chips. This technology can improve performance due to memory band widening and a reduction in the power consumed in inter-chip communications. This paper describes the concept, structure, process, and experimental results of prototypes of this package, called SMAFTI (SMAart chip connection with FeedThrough Interposer). This paper also reports the results of the fundamental reliability test of this novel inter-chip connection structure and board-level interconnectivity tests.

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MOS capacitors with Si-implanted thermal oxide and CVD deposited oxide of 30nm thickness were fabricated for applications of non-volatile memory and electroluminescence devices. Current-voltage (I-V) and I-V hysteresis characteristics were measured, and the hysteresis window (HW) and the integrated charge of HW (ICHW) extracted from the hysteresis data were discussed. The HW characteristics of high Si dose samples showed the asymmetrical double-peaks curves with the hump in both tails. The ICHW almost converged after the 4th cycle and had the voltage sweep speed dependence. All +ICHW and -ICHW characteristics were closely related to the static (+I)-(+V_G) and (-I)-(-V_G) curves, respectively. For the high Si dose samples, the clear hump currents in the static I-V_G characteristics contribute to lower the rising voltage and to steepen the ICHW increase, which correspond to the large stored charge in the oxide.

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This paper studies reflection and transmission of a TE plane wave from a two-dimensional random slab with statistically anisotropic fluctuation by means of the stochastic functional approach. By starting with a representation of the random wavefield presented in the previous paper [IEICE Trans. Electron., vol.E92-C, no.1, pp.77-84, Jan. 2009], a solution algorithm of the multiple renormalized mass operator is newly shown even for anisotropic fluctuation. The multiple renormalized mass operator, the first-order incoherent scattering cross section and the optical theorem are numerically calculated and illustrated in figures. The relation between statistical properties and anisotropic fluctuation is discussed.

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Based on provided convenient design equations for slow wave transmission lines and metamaterial line, a very compact rat-race hybrid coupler is proposed using three slow wave lines and one metamaterial line. At the design frequency of 2GHz, the size of the proposed coupler is 2.3cm × 2.7cm, which is a 74% reduction compared with the conventional one. Despite the considerable size reduction, the theoretical bandwidths based on |S₁₁|, |S₃₁|, ∠S₂₁-∠S₃₁, and ∠S₂₄-∠S₃₄, have been improved by 9%, 7%, 31%, and 59%, respectively. The measured performances are in reasonable agreement with the theoretical ones.

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A metallic waveguide that has an array of dielectric rods located at a distance from the side wall of approximately one quarter the waveguide width was previously proposed for single mode propagation over a wide frequency range. In this study, the S parameters of such a waveguide were measured for the TE₁₀ mode.

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This paper proposes a novel delay-locked loop (DLL) with fast-locking property. The improved fast-locking successive approximation register-controlled (IFSAR) scheme can decrease the locking time to n+4 periods and be harmonic-free, where n is the bits' number of the control code for a delay line. According to the simulation result in 180nm CMOS technology, the DLL can cover the operating range from 70MHz to 500MHz and dissipate 10.44mW at 500MHz.

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A novel bandpass filter (BPF) for an ultra-wideband (UWB) system is proposed in this letter. The BPF consists of four coplanar stripline (CPS)-to-microstrip transitions. Each transition is employed for broad electromagnetic (EM) coupling between a short-circuited CPS and an open-circuited microstrip line. The equivalent circuit model of the proposed geometry is derived and utilized in the impedance and mode matching analysis. Measured results show good agreement with the analysis and simulated ones.

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This paper presents a time amplifier design that improves time resolution using an inverter chain delay in SR latches. Compared with the conventional design, the proposed time amplifier has better characteristics such as higher gain, wide range, and small die size. It is implemented using 0.13µm standard CMOS technology and the experimental results agree well with the theory.

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