An innovative tri-axes micro-power receiver is proposed and studied for wireless magnetic energy transmission. The tri-axes micro-power receiver mainly consists of two sets of 3D micro-solenoids and one set of planar micro-coils in which individually iron core is all embedded. The three sets of micro-coils/micro-solenoids are designed to be orthogonal to each other. Therefore, no matter which direction the input magnetic flux is present along, the supplied magnetic energy can be harvested and transformed into electric power by the proposed micro-power receiver in wireless sense. Not only dead zone of receiving power is greatly reduced, but also transformation efficiency of magnetic energy into electric power can be much enhanced. By Biot-Savart law and Faraday’s law, the mathematical description upon power transmission from transmitter to receiver is developed. By employing commercial software, Ansoft Maxwell, based on finite element method, the estimation error on power transmission by mathematical description is revealed. Besides, the preliminary simulation results by Ansoft Maxwell show that the proposed micro-power receiver can efficiently harvest the energy supplied by magnetic power source. The design parameters of tri-axes micro-receiver are hence examined and verified for follow-up fabrication. At last, for the MEMS process, the isotropic etching technique is employed to micro-machine the inverse-trapezoid fillister so that the copper wire can be successfully electroplated. The adhesion between micro-coils and fillister is hence much enhanced as well.

In this paper, based on diffusion and thermionic-field emission conduction mechanisms in crystalline-insulator-crystalline system, a comprehensive model of current conduction for polycrystalline silicon is developed, considering the doping effect and the temperature effect on carrier mobility. The simulation results show a good agreement with the experimental data without unphysical fitting parameter. It is demonstrated that the effective diffusion velocity limits the carrier movement at light doping level, while the thermal velocity and the tunneling effect dominate the carrier conduction at heavy doping concentration. The developed model can interpret the conduction characteristics of polysilicon thin films over a wide range of doping levels with temperature.

Pure phase perovskite relaxor-based (1 – x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 (PMN–PT, x = 0.2–0.4) ferroelectric ceramics were prepared by the reaction-sintering method sintered at 1240–1250 °C. The synthesized ceramics exhibit rather homogeneous microstructure morphology and relatively high density. The content of PbTiO3 (PT) exerts successive influences on sintering capability, phase structure and electrical properties of the PMN-PT ceramics. With the increase of the PT content, the crystal structure of the PMN–PT ceramics changes gradually from the rhombohedral phase, across the coexistence of rhombohedral phase and tetragonal phase, and to the tetragonal phase, accompanied by the change of the dielectric response character from typical relaxor ferroelectrics to normal ferroelectrics. The morphotropic phase boundary (MPB) of the PMN–PT system is determined locating at x = 0.3–0.34 based on the structure analysis and the electrical properties measurements, in which the PMN–PT ceramics with the MPB composition exhibit enhanced microstructure and excellent electrical properties, especially superior piezoelectric properties.

We report on metal-oxide-semiconductor (MOS) AlGaN/GaN heterostructure field effect transistors (HFETs) based on InGaN/GaN multiple quantum well (MQW) structure using Ta2O5 dielectric deposited by electron beam evaporation (EBE) simultaneously for surface passivation and as a gate insulator. The device features a 5-pair MQW layer inserted into the AlGaN/GaN two-channel HFET structure. It results in a raised potential barrier, which leads to better carrier confinement and effective access to the InGaN layer. However, it revealed a pronounced leakage current which may be generated from the bottom Si-doped GaN and/or the sidewall leakage paths due to the exposure of channels after mesa etching. Both passivated MQW-HFET and MOS MQW-HFET present enhanced dc- and pulsed-mode performance compared to unpassivated one. In terms of transfer characteristics, MOS MQW-HFET exhibits the larger and broader main peak yet smaller satellite peak relative to passivated MQW-HFET. The reduced gate and mesa-to-mesa leakage current indicates the successful passivation effect from EBE-Ta2O5 dielectric.

We prepared the sputtered Co/p-InP Schottky diodes which consisted of as-deposited, and diodes annealed from 200 °C to 700 °C. The annealed samples were cooled from the annealing temperature down to room temperature, and then, their current-voltage (I-V) characteristics were measured. Schottky barrier height (SBH) at 300 K slightly decreases from 0.80 eV (for as-deposited sample) down to 0.77 eV (for the sample annealed at 400 °C) with the annealing temperature and then again increases up to 0.91 eV for the sample annealed at 700 °C. The I-V measurements were made in the sample temperature range of 60–400 K. It is seen that the SBH for each diode monotonically increases with increasing the sample temperature up to 400 K. In the sample temperature range of 60–400 K, the Co/p-InP SBD annealed at 400 °C has a lower ideality factor value than those of the as-deposited and 200 °C annealed SBDs at each sample temperature. Thus, remarkable apparent improvement of the diode parameters has been achieved by means of the thermal annealing. The improvement in the Co/p-InP interface due to the thermal annealing process has continued without deteriorating at each measurement temperature from 60 K to 400 K. Therefore, it has been concluded that the thermal annealing process translates the MS Schottky contacts into thermally more stable Schottky contacts.

The organic thin-film transistors (OTFTs) incorporating pentacene/SU-8 interface were fabricated and characterized. SU-8, a reliable epoxy-based photoresist, is tested as a potential highly-stable polymeric gate dielectric for OTFTs. The fabricated devices showed promising electrical performance with on-off ratio up to 107 and field-effect mobility up to 0.56 cm2/V s. Several device characteristics are further analyzed. There existed a leakage current path due to the uncontrolled pentacene coverage and we revealed that precise alignment of the evaporation mask of pentacene is critical for eliminating this problem. Pentacene grain formation largely depended on the growth condition on the SU-8 surface and small-grain films offered outstanding performance possibly owing to enhanced inter-domain connections. Natural degradation of the OTFTs is also discussed in terms of environmental stability and the pentacene/SU-8 transistor operated with noticeable air stability under ambient conditions.

In this paper, an nLDMOS and a pLDMOS are developed by slight modifications of the base process steps of 0.35 μm BiCMOS technology. Extra two masks are used for the formation of the body region and the drift region with slightly added thermal budget and without resorting to high-tilt implants. The specific ON-resistance (RON,SP) and the OFF-state breakdown voltage (BV) are 1.5 mΩ cm2 and 60 V, for the nLDMOS and 3.0 mΩ cm2 and 160 V, for the pLDMOS, so the devices can typically be operated around 42 V supply voltage, which is suitable for the new automotive applications. An isolation mechanism between the power devices is suggested using a deep trench filled with silicon dioxide and undoped polysilicon. The polysilicon has a nearly perfect conformal deposition, that is, both step coverage and bottom coverage are 100%. A simple subcircuit model is built using a two module approach, one for the intrinsic MOS area and the other for the drift region. The Spice model parameters of the intrinsic MOS part are extracted using a system that links the ICCAP extraction tool with the results of the ISE-TCAD tools. The simulation results using the Spice model are compared to the results provided by ISE-TCAD tools, and the accuracy at room temperature is less than 5% for the whole voltage domain. An interface circuit, to convert 0/3.3 V to 0/42 V, suitable for automotive applications, is proposed.

K1−xNaxHC4H4O6 · H2O (x = 0.3 and 0.7) single crystals have been grown by the gel encapsulation technique. The composition-related structural, optical and electrical properties are investigated. All the crystals have an orthorhombic structure. With the increase of Na content, the transparency of the crystals increases and the band gap values decrease. Good optical transmission of these crystals predicts them to be potential candidates for nonlinear optical applications. From the study on electrical conductivity, a semiconducting behavior is observed for these crystals. Resistivity, activation energy and hoping range are found to decrease with Na doping. DC conductivity behavior observed in these crystals is found to follow a variable-range hopping model. A clear indication of disorder induced in these crystals after Na doping is observed.

The influence of pressure on the MOCVD grown InAlN/AlN/GaN heterostructure has been investigated by high-resolution X-ray diffraction, Hall measurement and atomic force microscopy. High pressure is beneficial to increase indium incorporation efficiency. The electrical properties of InAlN/AlN/GaN heterostructure become better with the pressure decreasing from 100 Torr to 50 Torr. Indium droplets tend to form on the InAlN surface at high pressure. The edge of the indium droplet is the Al-rich region while the interior is the In-rich region, demonstrated by the phase-contrast mode. Phase contrast across the V-defect is strong on the surface of InAlN grown at low pressure (50 Torr) whereas it is not evident at high pressure (100 Torr), indicating that large stress in the InAlN film will enhance the compositional variation.

Thermal evaporation technique was used to prepare thin films of 5,10,15,20-tetraphenyl-21H,23H-porphine nickel (II), NiTPP, onto glass and quartz substrates. The crystal structures and morphologies of all prepared NiTTP thin films were investigated at 298, 423 and 573 K by using X-ray diffraction, XRD, and scan electron microscopy, SEM, respectively. The lattice of all prepared NiTPP films was investigated as a monoclinic with space group P2/M. The surface topography of the prepared films showed granular particles of sizes 49.7, 64.7 and 107 nm. The annealed NiTPP films at 423 K have a spatial configuration of well-defined grains boundary with nanoporous nature and all annealed films at 573 K have higher aggregates and the porosity of the films was increased. Optical constants namely refractive index, n, and the absorption index, k, of NiTPP films have been estimated by using spectrophotometric measurements of transmittance and reflectance in the spectral range from 200 to 2500 nm. The absorption spectra in the UV-vis spectrum were analyzed in terms of both molecular orbital and band theories. The obtained data of n and k were used to estimate the type of transitions and were found to be indirect transition for all films. The optical and fundamental gaps were decreased as the annealing temperature was increased. Some optical parameters namely molar extinction coefficient, εmolar, oscillator strength, f, and electric dipole strength, q2, have been evaluated. According to the single oscillator model and Drude model, some related parameters such as oscillation energy, Eo, the dispersion energy, Ed, the optical dielectric constant, ε∞, the lattice dielectric constant, εL, and the ratio of free carrier concentration to its effective mass, N/m∗, the third-order nonlinear susceptibility, χ(3), and molar polarizability, αp, were estimated before and after annealing.

We have performed an ab initio study of electronic and dynamical properties of the zinc-blende InSb at different electronic temperatures. The calculations have been carried out within the density-functional theory and linear-response formalism using norm-conserving pseudopotentials and a plane-wave basis. The calculated direct band gap is seen to be 0.1 eV, which is underestimated with the experimental value of 0.18 eV. As the electronic temperature increases, the results indicate that the InSb undergoes a melting transition to a metallic state. The transverse acoustic modes of the InSb are found to be negative in the most part of the Brillouin zone (BZ) which leads to lattice dynamical unstability at electronic temperature of 0.75 eV as indicated by imaginary phonon frequencies. Moreover, for optical modes, there exists a LO-TO splitting at the zone-center (Γ point) when Te = 0 eV and the frequencies are LO = 190.5 cm−1, TO = 182.4 cm−1, respectively; however, the LO-TO splitting will disappear when Te > 0 eV. The calculated values are in reasonable agreement with available experimental and theoretical data.

Nanocomposite TiO2-ZnO thin films, with different ZnO content, were deposited by electron-beam evaporation on glass and Si(1 0 0) substrates. The resulting films were annealed in air for 1 h at 450 °C. X-ray diffraction revealed the presence of monoclinic β-TiO2 and hexagonal ZnO for the films prepared with ZnO content of 0 at.% and 100 at.%, respectively. Mixed monoclinic β-TiO2 and hexagonal ZnO phases were observed at higher ZnO content between 50 at.% and 85 at.%. Spectroscopic ellipsometry (SE) was employed to determine the film thickness and optical constants. A two-layer model was used to describe the experimental ellipsometric data. At any wavelength longer than 390 nm, the refractive index decreases gradually with increasing ZnO content in the composite films. The optical band gap increased with increasing ZnO content. The photocatalytic behavior of TiO2-ZnO thin films was mainly evaluated by measuring the decomposition of methylene blue. The nanocomposite film with ZnO content of 8 at.% has the best photocatalytic activities.

Crystals of N-acetyl-L-cysteine have been grown by slow evaporation solution growth technique using water as solvent. Cell parameters of the crystals were confirmed by powder X-ray diffraction. Functional groups were identified and their vibrational activity was studied by investigating the FTIR spectrum. Decomposition nature of the grown material was studied in thermal analysis. Transparent nature of the crystal in UV-VIS-NIR region was examined by optical absorption spectrum. Frequency conversion process was tested and the title crystal has two times larger relative second harmonic conversion efficiency compared to the standard KDP. Static and dynamic values of first-order hyperpolarizability were calculated and also the electronic excitation mechanism was analyzed.

The dielectric dispersion of copolymer ferroelectric Langmuir-Blodgett thin film has been subjected to investigation using multiple-arc methodology with the associated relaxation time distribution. The analysis made use of reported data over the frequency range 10 Hz–2 MHz and over the temperature range of 308–398 K. The analysis indicated the presence of two distinct polarization modes corresponding to high- and low-frequency arcs. The modes have different characterizations in terms of the relaxation spread and mean time trends with temperature. The trends of the low-frequency arc with temperature support ferroelectric property for the thin L-B film. Satisfactory agreements have been realized between the experimental data and those derived by multiple-arc approach.

Magnetic properties of LaCoO3 nanoparticles prepared by a sol-gel method with average particle size (D) ranging from 20 to 500 nm are investigated. All samples exhibit obvious ferromagnetic transition. With decreasing particle size from 500 to 120 nm, the transition temperature Tc decreases slightly from 85 K, however Tc decreases dramatically when D ≤ 85 nm. Low-field magnetic moment at 10 K decreases with reduction of particle size, while the high-field magnetization exhibits a converse behavior, which is different with previous reports. The coercivity Hc decreases as the particle size is reduced. It is different with other nanosystems that no exchange bias effect is observed in nanosized LaCoO3 particles. These interesting results arise from the surface effect induced by sized effect and the structure change in LaCoO3 nanoparticles.

TiO2 nanorods, TiO2 nanorod/TiO2 nanoparticle and TiO2 nanorod/ZnO nanoparticle composite structures were integrated as photoanodes in backside illuminated dye-sensitized solar cells (DSSCs). Incorporation of TiO2 nanoparticles into the bare nanorods increased the dye loading and improved the short-circuit current density (Jsc) from 2.22 mA/cm2 to 3.57 mA/cm2. ZnO nanoparticles electrochemically grown into the TiO2 nanorod layer could increase the surface area. Nevertheless, this considerably reduced the Jsc to 0.57 mA/cm2 and consequently cell efficiency. Electrochemical impedance spectroscopy (EIS) results showed that ZnO incorporated samples have better effective diffusion coefficient of electrons in comparison with bare TiO2 nanorods while the recombination rate of injected electrons to photoanode with electrolyte is near eight times faster than bare TiO2 nanorods. ZnO incorporated samples showed lower electron density at steady state in the conduction band also. The worse performance of ZnO incorporated samples was attributed to lower electron injection efficiency from excited dye molecules. Monitoring electron transport properties of the cells measured by EIS pointed out the crucial role of electronic structure of composite film components on the performance of cells. Our results showed that EIS technique could be used as an efficient characterization method for precise monitoring of charge transport in nanocomposite photoanodes for DSSCs.

Thin Zn0.98Mn0.02O films were grown by pulsed laser deposition on glass substrates under oxygen pressure. The structural properties were studied by X-ray diffraction and Raman techniques, while the conductivity was characterized by the Hall effect. The oxygen pressure during the growth seems to govern the structural and the electrical properties of the thin Zn0.98Mn0.02 films. In fact, the micron size grain and the resistivity of the Zn0.98Mn0.02O increase with the partial oxygen pressure. However, no evident effect was observed on the magnetic behavior. Electronic structure calculations were performed and magnetic moment carried by Mn atom was computed as well.

The stabilized fibers with different relative cyclization index were prepared by stabilization of electrospun polyacrylonitrile (PAN) fibers at temperatures of 275, 290 and 300 ºC. Then electrospun PAN-based carbon fibers were prepared by carbonization of the stabilized fibers at 700 ºC in a nitrogen atmosphere. The thermal property of as-spun fibers during the stabilization process was investigated by differential scanning calorimetry. The evolution of chemical structure and morphology of the PAN-based stabilized fibers was studied by Fourier transform infrared spectroscopy and scanning electron microscopy, respectively. Microwave electromagnetic properties of these carbonized fibers were investigated in the range of 1.5–18.0 GHz by the vector network analyzer. The reflection loss was calculated by the measured electromagnetic parameter. The results indicate that the stabilization has a significant effect on the electromagnetic and microwave absorbing properties of the carbon fibers.

The porosity type in spark plasma sintered alumina was studied by variable energy positron beam technique. The gamma ray energy spectra of interest in the region of the annihilation peak were analyzed by means of Compton-to-peak ratio and deconvolution into Gaussians of the Doppler broadened annihilation peak. The contributions of the two narrow Gaussians (centered and red-shifted) revealed difference in the porosity type according to the heating rate. The samples sintered at low heating rate showed open porosity. Closed porosity appeared at 1050 °C as a result of formation of isolated pores. For the samples sintered at high heating rate, closed porosity was found to be significant even at comparatively low sintering temperatures which was explained by a blocking effect at the sample free surface.

Existing implementation of perfectly matched layers (PML) constraining the computational volume in an electromagnetic modeling of open structures has been shown to be efficient. However, cases with absorbing materials inserted into PML require substantial amount of memory and calculation time spent on the computation of the field inside the PML layer. In this paper we are addressing these problems by introducing a new computational method. As the procedure requires some substantial amount of memory and operations to compute fields in the PML layer, the paper addresses these issues. The PML split-field equations are revisited yielding a reduction from four-term storage to only three. In addition, the new algorithm is used with a new hybrid MRTD-FDTD (HMRTD) method applied to various lossy structures, conjointly with a higher-order field evaluation. Results demonstrate the efficiency of the new PML algorithm as compared to current schemes.