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ThCr 2 Si 2 -type Ru-based superconductors LaRu 2 P 2 and LaRu 2 As 2 with T c ∼4 K and 7.8 K respectively have been reported very recently. Using the first principles method we investigate the detailed physical and superconducting properties including the structural properties, electronic properties, elastic properties and Thermodynamic properties of these superconductors. Our investigated lattice parameters accord well with the experimental result. The analysis of the electronic band structure and density of states (DOS) indicates the metallic nature of both the compounds emerges from the La and Ru and the study of chemical bonding implies that a mixture of covalent, ionic and metallic bonds exists in both the compounds. The study of the mechanical properties revels that LaRu 2 P 2 is brittle in nature while LaRu 2 As 2 demonstrates the ductile nature and both the compounds show anisotropic characteristics. Finally we determine the Debye temperature and detailed superconducting parameters indicating that both the compounds under study are phonon-mediated medium coupled BCS superconductors. [ABSTRACT FROM AUTHOR]

A complete mapping of 14 nm FinFETs performance over 200 mm wafers was performed and the pattern dependency of SiGe selective growth was calculated using an empirical kinetic molecule model for the reactant precursors. The transistor structures were analyzed by conventional characterization tools and their performance was simulated by considering the process related variations. The applied model presents for the first time a powerful tool for transistor community to predict the SiGe profile and strain modulating over a processed wafer, independent of wafer size. [ABSTRACT FROM AUTHOR]

A series of Eu 2+ /Mn 2+ /Tb 3+ doped LiSrPO 4 phosphors have been synthesized by the solid state reaction. The XRD results show that all phosphors have the pure hexagonal crystal structure, indicating the doping ions have no influence on the phase of LiSrPO 4 host. Under the excitation at 365 nm, LiSrPO 4 /Eu 2+ phosphors emit blue emission originating from the 4f 6 5d 1 → 4f 7 transitions of Eu 2+ . The Eu 2+ /Mn 2+ or Tb 3+ codoped LiSrPO 4 phosphors show not only the emission of Eu 2+ but also the red emission coming from the 4 T 2 → 6 A 1g transitions of Mn 2+ or green emissions induced by the 5 D 4 → 7 F j transitions of Tb 3+ . The increasing Mn 2+ or Tb 3+ concentration induces the decrease of Eu 2+ emission intensity, which suggests the energy from Eu 2+ to Mn 2+ or Tb 3+ in LiSrPO 4 host. For LiSrPO 4 :7 mol%Eu 2+ /5 mol%Mn 2+ /5 mol%Tb 3+ phosphor, the white light can be obtained under the 365 nm excitation. [ABSTRACT FROM AUTHOR]

Abstract: Since Hewlett–Packardʼs solid state implementation of a memristive system in 2008, a lot of research has begun to develop applications using this new component. As it is not available as a two terminal device yet, emulating circuits must be developed. Building on our previous work to develop an analog model of a memristor, a memcapacitor emulator is proposed in this Letter. This model can be realized by transforming a memristor emulator to a memcapacitor emulator. The characteristics of a memcapacitor are based on the theory proposed by L.O. Chua. The transformation process is described in detail in this Letter. Simulation and experimental results are given as well. [Copyright &y& Elsevier]

Abstract: The classical physics description long-channel undoped asymmetric independently driven double-gate MOSFETs channel potential has been modeled thus far by means of two types of equations consisting of either hyperbolic or trigonometric functions, as dictated by the applied bias conditions. Instead of such separate regional equations, we propose here the use of a single completely generic equation based on complex variables, which is valid for all values of front and back-gate bias. The unified nature of the proposed equation may be useful for future development of double-gate MOSFET modeling work because it provides a better basis for global physical insight. The solution of this equation is analyzed for several cases, including the all important fully symmetric one. [Copyright &y& Elsevier]

Abstract: Porous thin films deposited by glancing-angle deposition (GLAD) have found application as sensor, micro-electrical mechanical systems and microfluidic devices. However, conventional micro-fabrication techniques can damage the very properties which make GLAD films attractive for these applications. To facilitate integration of GLAD films with these processes, a capping layer may be used. Such capping layers must be as free of defects as possible to ensure that the GLAD film is well protected. Here, the cracking properties of evaporated TiO2 caps deposited on GLAD films have been investigated as a function of substrate temperature. Our films are a porous vertical post layer 2.7μm thick capped with a solid 400nm layer. This material system experiences tensile stress from two sources: thermal mismatch between the film and substrate, and intrinsic stress in the cap from Volmer–Weber coalescence. Crack properties such as crack length distribution, crack density and branch number were quantified. In general, higher substrate temperatures reduced crack density, branch number and preferentially eliminated longer cracks. The onset of crystallinity at substrate temperatures around 300°C briefly increases crack area and branch number, but a further reduction can be achieved by depositing above this temperature. Applications of films grown by GLAD requiring high-quality capping layers will benefit from this study. [ABSTRACT FROM AUTHOR]

Abstract: A new optical method for the characterization of magnetostrictive effects in bulk superconductors will be presented. Several of wavelength encoded fiber Bragg gratings can be inscribed in one fiber with small spatial distances, which gives the possibility to measure magnetostrictive effects spatially resolved. To demonstrate the performance, samples with Bragg grating arrays glued onto the surface of an YBCO disk where tested in a superconducting solenoid at temperatures of 60K and magnetic inductances of 6.5T. For the first time the radius position dependent strain and not only sum effects could be measured. It was stated that in the remnant state both, elongating and compressive strain, occur. This is in agreement with our simulations. [Copyright &y& Elsevier]

Abstract: The magnetic properties of low dimensional ferromagnetic systems have been widely investigated over the past decades, since they present exotic new features that cannot be obtained in bulk materials. Compared to ferromagnets, antiferromagnetic materials constrained in a low dimensional environment have received, by far, much less attention. This field, however, is now attracting a rapidly increasing interest, motivated by the availability of recently developed experimental techniques able to assess the magnetic properties of low dimensional antiferromagnetic systems, and by the fact that there is now a general consensus about the primary role played by the interface magnetic structure in systems where a ferromagnetic material interacts with an antiferromagnetic counterpart, as in the exchange bias effect. The purpose of this review is to give a summary of the recent achievements in the understanding of the magnetic properties of late 3d transition metal antiferromagnetic oxides thin films, interfaces and surfaces. Topics such as domain walls and micromagnetic structure, thin film anisotropy, exchange bias, antiferromagnetic–ferromagnetic coupling will be discussed. The analysis of these items will be carried out with the help of experimental results and theoretical models. [Copyright &y& Elsevier]

Abstract: Transparent conducting oxide thin film CdTe-doped indium oxide (In2O3) has been grown by pulsed-laser deposition from a target of CdTe powder embedded in metallic indium. The electro-optical and structural properties were investigated as a function of oxygen partial pressure (PO2) and substrate temperature (T s). A film deposited at T s=420°C and PO2=4Pa shows the minimum resistivity ∼7.5×10−4 Ωcm, its optical transmission is 83% and the carrier concentration was ∼8.9×1020 cm3. The optical band gap and the average roughness of that sample were 3.6eV and ∼6.45Å, respectively. X-ray diffraction studies indicated that the films were polycrystalline. This material is a good candidate for being used as transparent conductor in the CdTe–CdS solar cell. [Copyright &y& Elsevier]

Abstract: We investigated that in HgBa2Can-1CunO2n+2+δ [Hg-12(n-1)n], for n ⩾6, T c of about 105K, vortex melting lines remains constant and independent of number of inner plane CuO2 layers. However the vortex dynamics of the supermultilayer system could be crucially different from that of single or double layer cuprates. Therefore we measured the fundamental and third harmonic AC susceptibility responses to see the vortex dynamics and vortex matter phase diagram of Hg-12(n-1)n (n =14), the higher member of super-multilayered cuprate superconductors. The Lindemann type vortex melting line was estimated using onset of third harmonic susceptibility (χ 3), at very low h AC (50 mOe), and represented by 3D Ginzburg Landau rescaling. Frequency dependence of out of phase susceptibility χ″(T) measured at lower fields of 500 and 1000Oe, for 10Hz to 10kHz, showed resonance behaviour in the temperature region 55–68K, suggesting rotational and translational creep dynamics of vortex molecule, even below usual melting line. We present schematic vortex phase diagram, considering the response of vortex dynamics to applied AC frequencies, taking into account the crossover temperatures obtained from critical slowing down of spin glass model and extended thermal activated model. [Copyright &y& Elsevier]

Abstract: The influence of and UV irradiation on the optical properties of thin film chalcogenide glasses has been studied. An increase in the optical energy gap is observed after -irradiation with an exposure dose higher than 100kGy and up to 1050kGy. The results of -irradiation are discussed in terms of the structural aspects of glass system. Photo-induced changes of the optical properties by UV-irradiation are also analyzed. The observed changes are associated with the interaction of the incident photon and the lone-pairs electrons which affects the band gap of the system. The changes in band tail width of the localized state after irradiation with or UV are found to have an opposite trend compared with the changes in the optical band gap. The X-ray structural characterization revealed the amorphous nature of the films before and after and UV irradiation. [Copyright &y& Elsevier]

Abstract: Present work explored a room temperature, simple and low cost chemical route for the cobalt oxide film onto copper substrate from cobalt chloride (CoCl2·6H2O) precursor and characterization for its structural and electrochemical properties for supercapacitor application. The morphology and crystal structure of the film were investigated by scanning electron microscopy and X-ray diffraction techniques, respectively. The electrochemical supercapacitive properties of cobalt oxide film were evaluated using cyclic voltammetry and galvanostatic charge–discharge methods. The film showed maximum specific capacitance of (165F/g) in 1.0M aqueous KOH electrolyte at scan rate 10mV/s. [Copyright &y& Elsevier]

Abstract: Lead zirconate titanate (PZT) thin films are deposited on platinized silicon substrate by sol–gel process. The crystal structure and surface morphology of PZT thin films are characterized by X-ray diffraction and atomic force microscopy. Depth-sensing nanoindentation system is used to measure mechanical characteristics of PZT thin films. X-ray diffraction analyses confirm the single-phase perovskite structures of all PZT thin films. Nanoindentation measurements reveal that the indentation modulus and hardness of PZT thin films are related with the grain size and crystalline orientation. The increases of the indentation modulus and hardness with grain size are observed, indicating the reverse Hall–Petch effect. Furthermore, the indentation modulus of (111)-oriented PZT thin film is higher than those of (100)- and random-oriented films. The consistency between experimental data and numerical results of the effective indentation moduli for fiber-textured PZT thin films using Voigt–Reuss–Hill model is obtained. [Copyright &y& Elsevier]

Abstract: CdIn2O4 thin films were prepared by direct-current (DC) reactive magnetron sputtering. The structure, surface morphology and the chemical composition of the thin films were analyzed by X-ray diffraction (XRD), atomic force microscope (AFM) and X-ray photoelectron spectroscopy (XPS), respectively. The electrical properties of the films prepared in different oxygen concentration and annealing treatment were determined, and the effects of the preparing conditions on the structure and electrical properties were also explored. It indicates that the CdIn2O4 thin films with uniform and dense surface morphology contain mainly CdIn2O4, In2O3 phases, and CdO phase is also observed. The XPS analysis confirms the films are in oxygen-deficient state. The electrical properties of these films significantly depend on the preparing conditions, the resistivity of the films with the oxygen concentration of 4.29% is 2.95×10−4 Ωcm and the Hall mobility is as high as 60.32cm2/Vs. Annealing treatment can improve the electrical performance of the films. [Copyright &y& Elsevier]

Abstract: Technology processes of thin metal films deposition are entailed with changes in material’s microstructure. As a result, deposited films often are characterized with material properties, which are different from these of the original bulk material. Determination of these material characteristics is of big importance for practice. In the present work the material properties of thin bright copper film with known depth were investigated. The film was deposited electrochemically over substratum composed of metallurgic brass alloy (CuZn36). Based on the results from microindentation test the load–displacement curve is obtained after the indenter is unloaded and the imprint diameter is measured. Consequently the process of indentation was modelled numerically. The numerical simulation is based on the finite element model of the indentation process. As a result of the simulation the load–displacement curve was obtained numerically for a certain set of material parameters. The trial–error approach is applied to find most appropriate set which fit the experimental load–displacement curve. At the end results, which were obtained through numerical simulation give good coincidence with the experiment. Therefore the proposed method can be successfully applied for identification of material parameters of the accepted model. The proposed trial–error approach is appropriate for investigation of thin films with known thickness, deposited on a substrate with known material characteristics. [Copyright &y& Elsevier]

Abstract: Nanocrystalline ZnS thin films are prepared on glass and quartz substrates by sulfurizing ZnO thin films in the H2S-containing mixture at 500°C. These films are investigated by X-ray diffraction, scanning electron morphology, optical transmittance and photoluminescence spectra. The results show that the ZnS thin films have the hexagonal structure with a c-axis preferred orientation. Also, these nanostructure ZnS thin films with the grain size of ∼50nm along the c-axis, exhibit the optical transparency as high as ∼80% in the visible region. It is found that sulfur replacement of oxygen sites in crystal lattices and recrystallization can take place during sulfidation, resulting in an evident increase of the grain size for the sulfurized films. Under the optimum sulfidation time of 2h, the resultant ZnS thin films have a high crystallinity, low defect concentration and good optical properties with the band gap of 3.66eV. [Copyright &y& Elsevier]

Abstract: We prepared highly transparent nanocomposite films with high refractive index using fluorescent nanocrystal quantum dots (NQDs). The as synthesized transparent solution of ZnS NQDs was blended with poly(vinylpyrrolidone) (PVP) to prepare nanocomposite thin films. Morphological data, studied by atomic force microscopy (AFM) and X-ray diffraction (XRD), revealed that NQDs were impregnated with polymer matrix and the size distributions (3.0±0.30 nm) of them were preserved in the composite films. The nanocomposite films show high optical transparency (T >95% at 400 nm and T >98.5% at 750 nm) and the refractive index is satisfactorily increased (1.565 at 550 nm, 15 wt.% ZnS) compared to the base polymer (1.480 at 550 nm). The nanocomposite films show defectless fluorescence emissions as observed from NQDs before impregnation. [Copyright &y& Elsevier]

Abstract: Thin films become an important technology because of its outstanding performance in wide engineering applications. The basic of thin film technology is to characterize its mechanical properties, which are strongly dependent on the internal stresses induced by deposition processes. Therefore, an investigation of mechanical properties of thin films affected by internal stresses is presented. In this work, titanium thin films are deposited on silicon wafer substrate by evaporation deposition. Internal stresses of thin films are measured by a surface profiler and the elastic modulus and hardness of the thin films are tested by a nanoindenter with a standard Berkovich probe tip. Corelation between the internal stresses and mechanical properties are also discussed. [Copyright &y& Elsevier]

Abstract: We report the fabrication of specially-designed Schottky rectifiers with thin Schottky metal on bulk GaN substrate through a homoepitaxial process. The Schottky rectifiers show consistent easy turn-on behaviors but with a wide distribution of reverse leakage current levels. A turn-on voltage as low as 0.9V with a low on-resistance of 2.56mΩcm2 was obtained. The easy turn-on properties can be attributed to the low series resistance achieved by fabricating vertical geometry devices on highly conductive GaN substrate. Electron-beam induced current analysis indicates that although the dislocation density in the homo-epilayer is generally low and on the order of ∼1×107 cm−2, mesoscopic defects such as grain boundaries and “dislocation walls” are present in the epilayer and serve as strong recombination centers. By comparing the reverse leakage current levels and the EBIC images of selected devices, we found that the “dislocation walls” observed are most likely to be the major source of high reverse leakage current. This study not only shows the promise of making high-performance GaN power devices based on homoepitaxial growth approach, but also indicates the importance of successful substrate polishing to the development of bulk-GaN-based devices. [Copyright &y& Elsevier]

Abstract: The dependence of hot-carrier effects on silicon film thickness is investigated in nanometer-scale SOI pMOSFETs. The results of device simulation and experimental measurements shine light on controversial issues regarding the dependence of hot-carrier effects on the silicon film thickness. For a structure with raised source and drain, it is observed that the peak electric field near drain junction and the gate current increase as the silicon film thickness decreases, and thus that hot-carrier effect are increased. Therefore, hot-carrier induced device degradation in nanometer-scale MuGFETs with elevated source/drain structure should be seriously considered in device design and fabrication. The dependence of hot-carrier effects on silicon film thickness under different stress conditions involving the action of substrate bias and temperature are also discussed. [Copyright &y& Elsevier]

Abstract: A physics-based low frequency noise model has been developed for MOSFET devices with nitrided high-κ gate dielectric materials. The new model is built upon the correlated carrier number and surface mobility fluctuations theory, where the original Unified Model was modified to take into account the multilayered structure of the high-κ gate dielectrics, and the resultant charge carrier tunneling process in terms of a two-step cascaded barrier instead of a single step barrier. The new model eliminates the discrepancies previously reported for the dielectric trap density values extracted from noise data using the original Unified Model for flicker noise. The dielectric trap density, typically taken as an average or spatially uniform in the dielectric and constant with respect to energy, is replaced here with an exponential expression dependent on the band-gap energy along with a spatial distribution of the traps in the high-κ layer. Thus, due to the energy dependence of the trap density, bending of the energy bands induces an additional non-uniformity in the spatial trap distribution. Implementation of this expression also provides the much needed flexibility in simulating realistic trap profiles in high-κ materials. Here, MOSFETs with nitrided dielectrics were considered for the noise experiments, as nitridation presents many advantages for the electrical and thermal characteristics of the gate insulator. Variable temperature low frequency noise and mobility measurements have been performed on MOSFETs with nitrided high-κ dielectric. Phonon scattering was found to have a profound effect on the mobility behavior, but no consequence on the low frequency noise characteristics. The low frequency noise data obtained on devices with different interfacial layer thicknesses and different regions of transistor operation was successfully compared with the predictions of the newly developed Multi Stack Unified Noise (MSUN) Model over a temperature range of 172–300K. [Copyright &y& Elsevier]

Abstract: For fully-depleted SOI MOSFETs, fabricated in standard and strained 65nm technologies, it is observed that the drain current I normalized for the device length L and width W levels off at sufficiently high gate voltage overdrives. Also the normalized drain current 1/f noise spectral density S I shows a plateau value for high front gate voltages. For both strained and non-strained devices there exists a relation between the two plateau values and a y ∼(x)1/4 law is found for the experimental data where , y = I plateau (L/t W), and I plateau are the plateau values of S I and I, respectively, and N ot is the density of the oxide traps responsible for the 1/f noise observed. Compared to standard SOI the use of strained SOI (sSOI) increases the magnitude of the plateau and makes its dependence on the device geometry more pronounced, while the impact of a strained contact etch stop layer (sCESL) is limited. The experimental observations are explained by taking into consideration the field and geometry dependence of the mobility and the influence of negative oxide charges on the drain current. [Copyright &y& Elsevier]

Abstract: The effect of gate-length variation on DC and RF performance of InAs/AlSb HEMTs, biased for low DC power consumption or high gain, is reported. Simultaneously fabricated devices, with gate lengths between 225nm and 335nm, have been compared. DC measurements revealed higher output conductance g ds and slightly increased impact ionization with reduced gate length. When reducing the gate length from 335nm to 225nm, the DC power consumption was reduced by approximately 80% at an fT of 120GHz. Furthermore, a 225nm gate-length HEMT biased for high gain exhibited an extrinsic fT of 165GHz and an extrinsic f max of 115GHz, at a DC power consumption of 100mW/mm. When biased for low DC power consumption of 20mW/mm the same HEMT exhibited an extrinsic fT and f max of 120GHz and 110GHz, respectively. [Copyright &y& Elsevier]

Abstract: We have investigated the electronic and optical properties of zincblende InP at ambient and under hydrostatic pressure using the full potential linear augmented plane wave (FP-LAPW) method. The pressure dependence of the energy gaps along different symmetry directions have been found to obey the equation . The pressure coefficients are in agreement with experiment. The valence bandwidth increases with increasing pressure which results in increased covalent character. The optical properties have been calculated and compared with ellipsometric measurements. The variation of band gaps with respect to the application of pressure and the origin of structures in the optical spectra are discussed in terms of the band structure. [Copyright &y& Elsevier]

Abstract: In this paper, an improved layout and thermal management of eight unit-cells SiGe power HBT with emitter area of 8×0.6×10μm2 were designed for high power density and efficiency performance. The on-wafer power characteristics were measured using an ATN load-pull system under class-AB operation at 2.4GHz. The power HBT achieved a 1-dB compression power (P −1dB) of 27.3dBm and a saturation output power (P sat) of 30dBm which was correspond to a power density of 2.6mW/μm2 for the emitter area. A high peak power added efficiency (PAEmax) of up to 75% was obtained, with a power gain of 11.4dB at a P 3-dB of 29.0dBm. In addition, the real part of the source impedance (R in) was measured to be as high as 28Ω. The impedance transfer ratio, R in/R System is only 0.56 which relaxes the need for a high quality passive component (inductor) for on-chip input matching. This advantage makes it easier for the HBT to be integrated with other silicon-based transceiver in an RF System-on-Chip (SoC) design. [Copyright &y& Elsevier]

Abstract: A new analytical polysilicon thin film transistors (poly-Si TFTs) subthreshold current model is presented in this paper. The model is based on the surface potential in subthreshold regime. When assuming an exponential distribution of defect states density, surface potential calculation is derived by using the Lambert W function, which benefits from computational efficiency and is suitable for implementation in circuit simulation. In order to model the subthreshold characteristics, we have calculated the drain current and subthreshold swing. The subthreshold variation with temperature and kink effect is studied. The off-current around flat-band voltage is also calculated. The results are compared with the available experimental data and an excellent agreement has been obtained. [Copyright &y& Elsevier]

Abstract: A novel low phase-noise differential Colpitts VCO by using transformer feedback technology is presented in this paper. This work demonstrates a simple differential topology with dual-transformer approach to reduce phase-noise at low DC power consumption. A symmetrical circuit layout can be realized easily by transformers and a commonly cross-coupled structure is not adopted herein because cross couple feedback path is also a serious parasitic effect more at 10GHz operation. Therefore, dual-transformers provide a compact feedback path and DC feed path simultaneously. Consuming a DC power of 8mW in the VCO core, the circuit exhibits a phase-noise of −115dBc/Hz at offset frequency of 1-MHz and the figure of merit value is −184.1dBc. [Copyright &y& Elsevier]

Abstract: The thermal behavior of trench-isolated structures on SOI (silicon-on-insulator) substrates is analyzed. Detailed 3-D numerical simulations have been performed to investigate the impact of all technological and material parameters of interest. A novel analytical model for the temperature field is proposed, which is based on the reduction of the domain under analysis to a silicon rectangular parallelepiped with convective boundary conditions at lateral and bottom faces. An extensive comparison with numerical results proves that the model is extremely accurate in the overall parameter range, and can be adopted for a fast evaluation of the thermal resistance of a trench SOI device as well as of the temperature gradients within the silicon island surrounded by trenches and buried oxide. [Copyright &y& Elsevier]

Abstract: This paper analyzes the design tradeoffs between Si and SiGe MITATT diodes using a Monte Carlo method. The narrow bandgap material Si0.7Ge0.3 improves the charge confinement in the avalanche generation region and therefore increases the RF power generation efficiency. A SiGe MITATT diode operating at 200GHz can produce 42mW of RF power which is 63% higher than that from a Si MITATT diode. Beyond 300GHz, the superior thermal properties of Si allow the Si MITATT diode to be driven at higher DC power level. Therefore, 2.3mW can be generated from the Si MITATT diode at 400GHz but only 1.5mW from the SiGe MITATT diode. [Copyright &y& Elsevier]

Abstract: The application of the capability of low-temperature poly-Si TFT circuits for high resolution X-ray active matrix sensor is explored. The integration of poly-Si TFT circuits on the glass enables an easy connection for the sensor array with fine pixel pitch. A novel charge sensitive amplifier circuit employing poly-Si TFTs is proposed for the readout system of the active matrix sensor. It can considerably increase the circuit’s immunity to the unavoidable threshold voltage variations of the poly-Si TFTs. The V TH mismatch effect of the TFTs, which results in the offset voltage of the charge amplifier, can also be suppressed by the proposed circuit. However, the noise arisen from the V TH mismatch can be even larger than that from the V TH variation after compensation. It reflects that, for higher bit digital X-ray image sensors, the mismatch effect of the devices must be properly taken into consideration. [Copyright &y& Elsevier]

Abstract: A series of congruent crystals Zn:Ce:Cu:LiNbO3 crystals doped with Zn(0,3,5,7mol%) were grown by using Czochralski method. OH− vibrational band and fundamental absorption edge were used to deduce the defect structure. Photorefractive properties were measured by two-wave coupling and light induced scattering experiments. It was found that the response and erasure time shorten with the increase of Zn doping concentration, whereas threshold intensity to optical damage of Zn(7mol%):Ce:Cu:LiNbO3 was two orders of magnitude higher than that of Ce:Cu:LiNbO3. In this paper, site occupation mechanism of impurities were also discussed to explain the high resistance ability to optical damage and fast response speed in the Zn:Ce:Cu:LiNbO3 crystal. [Copyright &y& Elsevier]

Abstract: The effects of the composition of oxynitride passivations (SiO x N y ) deposited by plasma enhanced chemical-vapor deposition (PECVD) at room temperature on the microwave performance of AlGaN/GaN high electron mobility transistors (HEMTs) were investigated. Five different SiO x N y passivating layers were deposited covering the whole range of dielectrics combinations from SiO x to SiN y . Their impacts on the HEMT performance were studied by means of DC, S-parameters, pulsed IV and load-pull measurements. The oxynitride dielectric with a refraction index of 1.58 was shown to be an effective SiO x N y passivation for limiting the gate-lag effects in the HEMTs and at the same time increasing the breakdown voltage of the device. It is thus a promising passivation layer for microwave power high voltage and high power applications. [Copyright &y& Elsevier]

Abstract: Low-frequency noise in MOCVD-grown AlGaN/GaN/AlGaN/GaN double channel high electron mobility transistors (HEMTs) on sapphire substrate was investigated over a wide range of temperatures from 80K to 300K. Generation–recombination (g–r) noise was observed arising from the traps with activation energies 140meV, 188meV and 201meV. Hooge parameter was estimated to be 1.6×10−3 at room temperature. Our work demonstrates good dc and low-frequency noise properties for the device. [Copyright &y& Elsevier]

Abstract: We have performed a fully 2-dimensional (2D) Poisson, Schrödinger and continuity equations modeling of nanometer gate HEMTs. For the electron density n(x, y) in the channel we use the discrete levels obtained from the Schrödinger equation and the corresponding 1D density of states (DOS), so that a fully quantum representation of n is obtained. The threshold voltage reduction ΔV T we obtain at small V DS is in very good agreement with experimental values. By comparison with our classical calculations (a subset of our model) we deduce that quantum effects are not important for the calculation of ΔV T. However quantum effects become increasingly important as V GS increases beyond V T at small V DS .The deviation between classical and quantum values in the current are of the order of 40–80% depending on the device. As V DS increases and reaches saturation this percentage deviation decreases but its absolute value (in mA/mm) increases. These effects become more acute as the gate length becomes shorter. [Copyright &y& Elsevier]

Abstract: In this paper, we present a new method to measure light intensity in a floating body partially depleted SOI MOSFET. The photo-generated charge density in the MOSFET is converted into a charge pumping frequency needed to maintain the drain current at a constant value. This new approach contrasts with conventional techniques that rely on an accurate drain current evaluation. According to our measurements, flux densities as low as 2mW/m2 were obtained using a regular SOI MOSFET, thus confirming the potentials of this approach. [Copyright &y& Elsevier]

Abstract: Stress intensities of a singular near-tip field around the vertex of a triple junction wedge in multilevel thin film packages are calculated using the two-state M-integral. For this calculation the existence of a simple auxiliary field in the sense of the M-integral associated with every eigenfunction for the triple junction vertex is first verified numerically. The auxiliary field is then employed for superposition with the elastic field under consideration, and the associated two-state M-integral is computed via the domain integral technique. This enables us to extract the stress intensity of each singular eigenfunction for the triple junction vertex at three different junction angles, α =45°, 90° and 135°. [Copyright &y& Elsevier]

Abstract: Optical properties of thin films in the GeSe2–Sb2Se3–PbSe system are studied as a function of the PbSe content and at different ratio GeSe2/Sb2Se3. Transmission spectra of thin films are investigated. From the above spectra the absorption coefficient α for different PbSe content are derived. The increase of the absorption coefficient α is attributed to the increase of the current carriers density in the valence band. Optical band gap of the samples is determined using Tauc’s procedure. A correlation between the optical band gap and the composition of these chalcogenide samples could be seen. This might result from the increasingly stronger metal character of the bond that leads to the formation of a complicated band gap structure. [Copyright &y& Elsevier]

Abstract: Single phase Pb1−x Fe x Se () thin films, with typical rocksalt structure, are grown by the chemical bath deposition method. An additional segregated phase of Fe2O3 is observed in the films. The average grain size in the films grown at a fixed bath temperature is observed to remain constant with increase in Fe concentration from to . A decrease in , for fixed x, results in a decrease in grain size in the films. The induced decrease in grain size is seen to result in an increase of direct optical band gap in films with the same . In the typical case of films, decrease in grain size from 9 nm to 3 nm due to change in from 85 to 55 ∘C, results in an increase in from 2.09 eV to 2.89 eV. The blue shift is attributed to enhanced quantum confinement in the nanograins. However, at a fixed , while grain size remains constant with increase in , is observed to decrease. is seen to decrease from 2.20 to 1.84 eV with change in from 0.02 to 0.07 in of 85 ∘C films. This decrease is attributed to tailoring of due to alloying between PbSe and FeSe in the single-phase nanoparticle films of Pb1−x Fe x Se. Resistivity decreases while Hall mobility increases with the increase in () in the films. [Copyright &y& Elsevier]

Abstract: Taken into account inter-wall interaction and outer-wall disorder, we explore the persistent current in a multi-walled carbon nanotorus (MWCNT) within the tight-binding formalism. The calculations show that the inter-wall interaction induces dramatic changes in the energy spectra of both armchair and zigzag MWCNTs such as level splitting, level crossings and/or anticrossings, and even an energy gap opening at the Fermi energy, which leads to a decrease of persistent current and changes in the shape of the flux-dependent current. In the presence of outer-wall disorder, it is found that in the regime of weak disorder, the persistent current decreases with disorder strength, while it increases in the regime of strong disorder. The results show that MWCNTs may be a promising candidate for realizing a new type of surface-doping-like molecule devices. [Copyright &y& Elsevier]

Abstract: Tantalum nitride thin films were deposited by radio frequency (RF) reactive sputtering at various N2/Ar gas flow ratios and working pressures to examine the change of their electrical resistivity. From the X-ray diffraction (XRD) and four-point probe sheet resistance measurements of the TaN x films, it was found that the change of the crystalline structures of the TaN x films as a function of the N2 partial pressure caused an abrupt change of the electrical resistivity. When the hexagonal structure TaN thin films changed to an f.c.c. structure, the sheet resistance increased from 16 Ω/sq to 1396 Ω/sq. However, we were able to control the electrical resistivity of the TaN thin film in the range from 69 Ω/sq to 875 Ω/sq, with no change in crystalline structure, within a certain range of working pressures. The size of the grains in the scanning electron microscopy (SEM) images seemed to decrease with the increase of working pressure. [Copyright &y& Elsevier]

Abstract: Hybrid thin films have been deposited on silicon substrates under several conditions such as different annealing temperatures and RF power by plasma enhanced chemical vapor deposition method using single molecular precursors. The result of the FT-IR measurement showed that the plasma polymerized thin films have highly cross-linked density with increasing RF power and annealing temperature. An impedance analyzer was utilized for the measurements of I–V and C–V curves. From the electrical properties measurements, the lowest dielectric constant and best leakage constant were obtained to be 2.26 and 10−9 A/cm2 at 1 MV/cm, respectively. Also, the mechanical properties of the films were determined with nano-indentation. [Copyright &y& Elsevier]

Abstract: In the present study yttrium stabilized zirconia (YSZ) thin films were deposited on the Alloy-600, optical quartz and porous Ni–YSZ substrates using e-beam deposition technique controlling deposition parameters: substrate temperature and electron gun power. These parameters are influencing the thin film deposition mechanism. The dependence of substrate temperature and electron gun power on thin film ionic conductivity, structure and surface morphology was investigated by X-ray diffraction, scanning electron microscopy (SEM). It was found that electron gun power has influence on the crystallite size and growth of YSZ films. Dominating dispersion in the deposited YSZ thin films (substrate temperature T =250 °C, e-beam gun power P =0.9 kW) relates to ionic transport in the crystallites in the measured frequencies and temperature ranges. The measured values of conductivity (9.6÷41.2×10−4 Sm−1) and activation energies of conductivity (0.87÷1.1 eV) at 387 °C temperatures are typical to the polycrystalic ZrO2 — 8 mol% Y2O3 compound. The conductivity values of crystallites of YSZ thin films and ceramic are similar. To find out about the stability of formed YSZ thin films and to understand the influence of high temperature on crystallite size was done thermal annealing at 1100 °C temperature. It was found that crystallite sizes increases in size after annealing (3÷18 nm) and that depends on substrate temperature and e-beam gun power during the formation of YSZ thin films and crystallographic orientation of crystallite. [Copyright &y& Elsevier]

Abstract: Fe x Pd1−x films were epitaxially grown on Au(001). The structure changes from face-centered-cubic (fcc) to face-centered-tetragonal (fct) at , then to body-centered-cubic (bcc) at . Ferromagnetism shows up at 300 K when x is 0.06. The cubic magnetocrystalline anisotropy constant switches from negative to positive as x increases to 0.34. [Copyright &y& Elsevier]

Abstract: A new photochromic ZrO2 precursor solution was prepared using zirconium tetra-n-butoxide, 4-(phenylazo)benzoic acid and ethyleneglycol monomethylether. The density functional theory (DFT) calculation has identified that the structure of the synthesized precursor molecule changed by UV irradiation. Four types of thin films were prepared using the ZrO2 precursor solution with and without UV irradiation and applying an electric field. It was found that the surface morphology of thin films changed by applying UV irradiation to the precursor solution and an electric field. [Copyright &y& Elsevier]

Abstract: The temperature dependences of electrical conductivity, σ, and Seebeck coefficient, S, for some new pyridium monoquaternary salts derivatives, 1-(p-R-phenacyl)-4-{[(1′-ethylcarboxylate)-(3′-p-R′-phenacyl)]-7′-indolizinyl}pyridinium bromides have been studied. The film samples (d =0.08–0.28 μm) have been deposited onto glass by an immersion technique (dimethylformamide was used as a solvent). The investigated compounds behave as typical p-type polycrystalline semiconductors. The activation energy of electrical conduction ranged between 0.65 and 1.72 eV, while the ratio of charge carrier mobilities laid in the range (0.60–0.83). The model based on band gap representation is suitable in explaining the electronic transport in present compounds in the higher temperature range (385–500 K). [Copyright &y& Elsevier]

Abstract: ZnO thin films were prepared on fused silica from a single spin-coating deposition of a sol–gel prepared with anhydrous zinc acetate [Zn(C2H3O2)2], monoethanolamine [H2NC2H4OH ] and isopropanol. Crystallization annealing was performed over the range 500 to 650 °C. X-ray analysis showed that thin films were preferentially orientated along the [002] c-axis direction of the crystal. The films had a transparency of greater than 85% in the visible region for sol–gels with a zinc content of up to 0.7 M and exhibited absorption edges at ∼378 nm. The optical band-gap energy was evaluated to be 3.298–3.306 eV. Photoluminescence showed a strong emission centered at ca. 380 nm along with a broad yellow-orange emission centered at ca. 610 nm. Single step sol–gel thin film deposition in the film thickness range from 80 nm to 350 nm was demonstrated. The effect of sol–gel zinc concentration, film thickness and crystallization temperature on film microstructure, morphology and optical transparency is detailed. A process window for single spin coating deposition of c-axis oriented ZnO discussed. [Copyright &y& Elsevier]

Abstract: Transparent wide band gap indium molybdenum oxide (IMO) thin films were rf sputtered on glass substrates at room temperature. The films were studied as a function of sputtering power (ranging 40–180 W) and sputtering time (ranging 2.5–20 min). The film thickness was varied in the range 50–400 nm. The as-deposited films were characterized by their structural (XRD), morphological (AFM), electrical (Hall Effect measurements) and optical (visible-NIR spectroscopy) properties. XRD studies revealed that the films are amorphous for the sputtering power ≤100 W and the deposition time ≤5 min, and the rest are polycrystalline with a strong reflection from (222) plane showing a preferential orientation. A minimum bulk resistivity of 2.65×10−3 Ω cm and a maximum carrier concentration of 4.16×1020 cm−3 are obtained for the crystalline films sputtered at 180 W (10 min). Whereas a maximum mobility (19.5  cm2 V−1 s−1) and average visible transmittance (∼85%) are obtained for the amorphous films sputtered at 80 W and 100 W respectively for 10 min. A minimum transmittance (∼18%) was obtained for the crystalline films sputtered at 180 W (∼305 nm thick). The optical band gap was found varying between 3.75 and 3.90 eV for various sputtering parameters. The obtained results are analyzed and corroborated with the structure of the films. [Copyright &y& Elsevier]

Abstract: It is shown that Beck and Mackey electromagnetic model of dark energy in superconductors can account for the non-classical inertial properties of superconductors, which have been conjectured by the author to explain the Cooper pair’s mass excess reported by Cabrera and Tate. A new fundamental scale of nature (the Planck-Einstein scale) for gravitation in low temperature condensed matter is proposed to host the gravitoelectrodynamic properties of superconductors. [Copyright &y& Elsevier]

Abstract: Mg–Ni multilayers and Ni-rich Mg thin films were deposited by electron gun and pulsed laser deposition, respectively. Samples were submitted to thermal treatment in deuterium or hydrogen atmosphere at 423K and ∼105 Pa pressure to promote the metal to hydride phase transition. The H chemical bonding in the multilayer samples, after annealing in H2 atmosphere, was examined by Fourier transform infrared spectroscopy: the obtained spectra suggest that the samples with the Mg:Ni=2:1 atomic ratio contain the Mg2NiH4 phase while the samples with lower Ni concentration contain both the MgH2 and the Mg2NiH4 phases. The effect of the Ni additive on the stability of the deuteride phase was studied by thermal desorption spectroscopy (TDS). The TDS spectra of the single-phase Mg2NiD4 samples show a TDS peak at 400K. The TDS spectra of the two-phase samples show both the D2 desorption peak at 400K and a second peak at higher temperature that we attributed to the dissociation of the MgD2 phase. The high-temperature peak shifts to lower temperatures by increasing the Ni content. It is suggested that in the two-phase samples, the lattice volumes having the Mg2Ni structure resulting from the dissociation of the Mg2NiD4 phase reduce the thermodynamic stability of the MgD2 phase. [Copyright &y& Elsevier]

Abstract: The forward bias current–voltage (I–V) characteristics of n-GaN Schottky diodes on sapphire substrate were investigated over a wide temperature range of 70–500K. For models based on localised regions of lowered Schottky barrier height, a distributed barrier height should be expected when these localised regions are comparable to or smaller in size than the depletion width. However, a suitable fit for the I–V curves, which exhibited anomalous two-step (kink) forward bias behaviour, was only obtained when modelling the leakier regions with a single reduced barrier height, by using a model of two discrete diodes in parallel. [Copyright &y& Elsevier]