Schottky barrier diodes based on a composite of polyaniline with titanium oxide (TiO2) were fabricated using aluminum as a Schottky contact and gold as an ohmic contact. The observed current-voltage characteristics can be satisfactorily fitted using the modified Schottky equation. The current-voltage characteristics were studied to explain the rectification generation of the diode. The diode shows non-ideal I-V behavior with an ideality factor greater than unity. The conduction mechanism was determined and a Schottky-type conduction process was defined. The diode parameters such as saturation current density and ideality factor were found to be 9.28 x 10−4 A/cm2 and 6.33, respectively.

The authors investigated the effects of annealing in Ar atmosphere at different temperatures (350–1100 °C) on the densification and leakage current characteristics of thermally oxidized SiO2 films on n-type 4H-SiC. A strong correlation between densification improvement and leakage current reduction was observed. Densification of the SiO2 films, which were characterized by spectroscopic ellipsometry, Fouriertransform infrared spectroscopy and atomic force microscopy, can be significantly improved after annealing at moderate temperature (600 °C). The leakage current is decreased by two orders of magnitude of the SiO2 thin film after annealing at 600 °C. Based on the studies, SiO2 film of the highest quality can be obtained after annealing at 600 °C. Improvements in the quality of the SiO2 thin films after annealing at 600 °C may be explained by the consumption and formation of carbon-related and oxygen-related defects during annealing.

ZnO nanocrystals doped with Fe2O3 have been synthesized by the calcination method. Ferromagnetic resonance (FMR) study of 0.3(Fe2O3/0.7(ZnO) nanocomposite has been carried out in the 4–300 K range. The presence of magnetic zinc ferrite ZnFe2O4 nanoparticles with an average crystallite size of 11 nm was identified by XRD. Temperature dependence of the resonance field, linewidth and the integrate intensity calculated from FMR spectra has been determined. Existence of two temperature regimes: high (above 50 K) and low (below 50 K) has been established, further divided into two temperature ranges. The results of FMR study of agglomerated ZnFe2O4 nanoparticles indicate an important role of magnetic interactions, both inter-particle (exchange and dipolar) and intra-particle connected with the core-shell magnetic structure.

Surface modification was performed on the indium-tin-oxide (ITO) thin films by oxygen inductive coupling plasma (O-ICP) and oxygen plasma immersion ion implantation (O-PIII). The electronic states of ITO surfaces were characterized by X-ray photoelectron spectroscopy (XPS). The observed peak shifts of O 1s, In 3d5/2 and Sn d5/2 core levels showed that the work function of ITO can be further enhanced by O-PIII treatment, compared with that of untreated and O-ICP treated surfaces. The deconvolution of O 1s spectrum and calculation of stoichiometry showed that the work function improvement should be attributed to the increase of effective oxygen content, namely, the elimination of oxygen vacancies. In addition, the measurement of Kelvin probe confirmed that an increment of the ITO work function by 1.1 eV was obtained on O-PIII treated sample and the results sustained our proposal.

In this study, the effect of Nd2O3 nano-islands on the critical properties of NdBa2Cu3O7–δ (Nd-123) superconductive thin films grown on Ni-W metallic substrates was investigated. Nd-123 superconducting ceramic materials were prepared by solid-state reaction technique and then this ceramic material was used as target for producing the Nd-123 superconductive thin films with pulsed laser deposition (PLD). Nano-islands were prepared with the deposition of Nd2O3 by PLD. The obtained superconductive thin films were characterized by X-ray diffraction (XRD) analysis, morphological investigations of atomic force microscopy (AFM) images, transport analysis such as Jc and R-T measurements by four-point probe (FPP). As a result of these analyses, it was determined that nano-islands have important role for the flux pinning and it provides the increase of about 32% for the critical current value (Jc).

Transparent conducting aluminum-doped and undoped ZnO thin films have been deposited by direct current (DC) sputtering technique from ZnO target onto glass substrate at room temperature and 400 °C. X-ray diffraction analysis shows that all films have a preferential growth along the c-axis of the hexagonal structure. The average grain size increases with the increasing deposition temperature and the doping of thin films. Analysis with AFM shows an improvement of the surface with the doping of thin films and deposition temperature. The root main square (RMS) surface roughness increases with deposition temperature. Al-doped ZnO (AZO) thin films have a lower electrical resistivity than that of ZnO thin films. 1/f noise measurement shows that ZnO thin film is more homogeneous than that of AZO.

CuInS2 thin films have been successfully prepared on Pyrex substrates using spray pyrolysis technique. In this work, we study the effect of the flow rate on the physical properties of CuInS2 thin films. X-ray diffraction pattern reveals the presence of tetragonal structure with (1 1 2) preferential orientation for CIS thin layers. Optical analysis by means of transmission T(λ) and reflection R(λ) measurements allows to determine the direct band gap energy value in the order of 1.44 eV, indicating that CuInS2 compound has absorbing properties favorable for applications in solar cell devices. Photoluminescence measurements are performed on CuInS2 crystals and the analysis reveals that the emission is mainly due to donor-acceptor pair transitions.

α-Bi2O3 thin films were deposited on different substrates by atomic layer deposition method. The results of X-ray diffraction, high-resolution transmission electron microscopy and X-ray photoelectron spectroscope correspond to α-Bi2O3. The Fourier transform infrared spectroscopy analyses indicate that the reaction is rather complete during the deposition. Optical properties of the films have been investigated using ultraviolet-infrared transmittance spectra in the temperature range of 8–300 K. It is found that the band gap Eg decreases from 3.12 to 3.03 eV with the temperature. The parameters αB and ΘB of the Bose-Einstein model are 69.3 meV and 293.9 K, respectively. The band narrowing coefficient dEg/dT is −0.435 meV/K at room temperature. The present results can be considerable for future application of Bi2O3-based electro-optic and wide temperature range optoelectronic devices.

Polyethylene glycol (PEG) and mercaptoethanol (ME)-capped CdSe nanoparticles (NPs) have been successfully prepared and systematic investigation on structural, optical and photocatalytic properties is presented. The intrinsic characteristics of resulting nanoparticles were studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-visible and photoluminescence (PL) spectrophotometer. Cubic phase, nearly uniform size (∼10 nm) and spherical morphology of the synthesized nanoparticles were established through XRD and TEM analysis. Spectroscopic measurements exhibit that capping agent can effectively tune energy band structure. ME-capped CdSe NPs exhibit higher light emission efficiency as compared to PEG capping. Photocatalytic activity of CdSe nanoparticles on methylene blue (MB) dye, a significant enhancement was observed in the photodegradation efficiency. A maximum degradation of MB dye (73.5%) was obtained.

Si-rich oxide/SiO2 multilayer films with different N2O flow rates have been deposited by plasma enhanced chemical vapor deposition technique, and Si quantum dot (Si-QD)/SiO2 multilayer films are obtained by 1100 °C annealing. Steady photoluminescence (PL) spectra show that the main optical emission mechanism changes from quantum confinement effect of Si-QDs to interface defect states with increasing the flow rate of N2O. Curve fittings of time-resolved PL spectra show that two log-normal decay time distribution bands are obtained, and both the most frequent life-times decrease with increasing the flow rate of N2O, while increase with the red shift of detecting wavelength. Analyses indicate that defect states density and size distribution of Si-QDs strongly influence the PL decay properties.

Aerogel nanoparticles prepared with various Al concentrations were used as a target for the deposition of (V,Al) co-doped ZnO films by rf-magnetron sputtering on glass substrates. The influence of Al content on the structural and the optical properties of the Zn(V,Al)O films was investigated by X-ray diffraction and spectroscopic ellipsometry (SE). It is found that all films exhibit one high intensity (0 0 2) peak, indicating that they have c-axis preferred orientation due to self-texturing mechanism. SE measurements, used to determine the complex pseudo dielectric functions, were carried out at room temperature in the 1–6 eV photon energy region. The excitonic edge of the fundamental band gap (E0) transition in the imaginary part of the dielectric function of the Zn(V,Al)O films is observed around 3.5 eV and shows a dependence on the Al content. The E0 absorption edge of the Zn0.9−x V0.1AlxO alloys shows a blueshift from that of pure ZnO, reaching 389 meV for x = 0.02. This blueshift is interpreted by the Burstein-Moss effect. By analyzing the dielectric function, reduced effective mass m* of the Zn0.9−x V0.1AlxO alloy is extracted and shows good agreement with literature values.

The crystallographic microstructure properties of Al-Ti alloys rapidly solidified by a vacuum melting process were investigated by XRD, SEM, optical observations and DSC analysis. It was found that the microstructures are polycrystalline fine-grained (typically 10—20 µm) of intermetallics in equilibrium with the solid solution Fcc α-Al(Ti) matrix.

Cu0.62Zn0.38 foil was subjected to surface mechanical attrition treatment (SMAT) processing first. Growth behavior of ZnO nanostructure on the SMAT Cu0.62Zn0.38 surface during thermal oxidation was investigated in this paper. The original and SMAT Cu0.62Zn0.38 foils were thermally oxidized at 400 ~ 700 °C under various gaseous environments, including nitrogen and mixture of N2-O2 at a pressure of 1 atm. for 3 h. The oxidized specimens were characterized with a scanning electron microscope, an X-ray diffractometer and a transmission electron microscope. It is found that nanosheets are easily formed on the SMAT specimen surface. The favorable formation of nanosheets relates to twin lamellae structure of Cu0.62Zn0.38 formed during SMAT processing.

Characteristics of the parametric γ-radiation (PGR) from relativistic electrons in Mössbauer crystals are analyzed in the framework of the kinematical diffraction theory taking into account the interference between electron and nuclear resonant parts of the crystal X-ray polarizability. Optimization of crystal parameters, electron energy and diffraction geometry is carried out in order to increase the brightness of the resonant γ-radiation source based on PGR. A possible experimental setup for observation of PGR is discussed.

Pulsed thermography has been proven to be a fast and effective method to detect fluid ingress in aircraft honeycomb structure; however, water and hydraulic oil may have similar appearance in the thermal image sequence. It is meaningful to identify what kind of liquid ingress it is for aircraft maintenance. In this study, honeycomb specimens with glass fiber and aluminum skin are injected different kinds of liquids: water and oil. Pulsed thermography is adopted; a recognition method is proposed to first get the reference curve by linear fitting the beginning of the logarithmic curve, and then an algorithm based on the thermal contrast between liquid and reference is used to recognize what kind of fluid it is by calculating their thermal properties. It is verified with the results of theory and the finite element simulation.

We report on the fabrication and optoelectronic features of Tb3+ doped gadolinium oxide (Gd2O3) nanpowders. The nanosystems were found to exhibit cubic crystalline structure with an average crystallite size in the range of 11–24 nm. Inclusion of Tb3+ into Gd2O3 host has led to suppression of the optical gap but resulted in the enhanced refractive index of the corresponding nanophosphor. In the PL spectra, apart from the oxygen defect related emissions, Tb3+ mediated (0.5% of doping level) improved radiative emissions owing to 5D4→7F6 and 5D4→7F5 transitions were found to be located at ∼492 and ∼548 nm; respectively. Rare earth ion doped rare earth oxide nanopowders may find immediate scope in smart optoelectronic elements and advanced nanometric phosphors.

The structural, electronic and magnetic properties of transition metal TM (TM = Fe and Co) monatomic nanochains encapsulated inside and between (6,6) boron nitride nanotube (BNNT) bundle have been investigated by the first-principles calculations in the framework of the density functional theory. Our results show that intercalation of TM chains leads to the significant changes in the geometrical structure. All TM chains TM-Chs@BNNT bundle systems have negative formation energy so they are stable and exothermic. It is found that all these TM-Chs@BNNTs bundle systems are ferromagnetic and a spin splitting between spin up and down is observed. The spin polarization and the magnetic moment of the systems depend on the position and the type of the transition metal atomic chains.

The presence of metallic particles has been recognized as a dangerous threat in gas-insulated substation (GIS). Such particles are initially free and move toward higher electric field regions such as triple junction i.e., spacer-electrode-gas interface. However, once these particles reach the spacer surface, they adhere to the spacer easily due to electrostatic image forces. From insulation point of view, the triple junction is the weakest point in GIS. The presence of such metallic particles on the spacer surface deteriorates the insulation strength. Thus, in order to improve the reliability of GIS, it is important to identify the size and the position of the particle adhering to the insulating spacer surface. One of the most promising methods to carry out such identification is by recognizing the partial discharges (PDs) provoked by such particles. This paper is aimed to discuss the particle size and position estimation by using the PD patterns and statistical analysis. The PD patterns were acquired using IEC 60270 method. Measurements were made to determine various PD signals caused by particle of different sizes at different locations on the spacer surface. The acquired PD patterns were characterized by a number of statistical parameters. The results show that the implemented technique could be used to distinguish between various particle sizes and positions at different SF6 pressures with a fairly high accuracy.

In this study, the properties of polypropylene fabrics grafted with chitosan after being activated by low temperature plasmas were evaluated. The chitosan was applied to polypropylene fabrics by using pad-dry cure technique. The surface morphology was characterized by SEM images. Treated samples were characterized by means of Fourier transform infrared (FTIR) spectroscopy. The polypropylene fabric treated with chitosan demonstrates an excellent dyeability property.

We are interested in modeling the interaction between light and biological tissue from the Monte Carlo method which is an approach used to solve modeling problems in different physical domains. Through the Monte Carlo approach we are going to try to interpret the spectral response absorption, reflectance, transmittance of normal human tissue under its three dominant tints in the visible range (350–700) nm. Then we will focus on the spectral response of the human tissue with varicosities in order to determinate the optimal conditions of operating the semiconductor laser for esthetic aim.