We show that commercial float glass can be used as a substrate to deposit polycrystalline silicon (poly-Si) by chemical vapor deposition from trichlorosilane at temperatures between 740 and 870 °C. By using scanning electron microscopy an average grain size lower than 0.4 μm was observed, with a columnar structure suitable for the electrical conduction in photovoltaic cells. X-ray diffraction reveals a strong (2 2 0) preferential orientation of the films, which is indicative of a low density of intra-grain defects. Atomic force microscope images reveal a conical structure, with a root mean square roughness of ~65 nm for samples of around 3 μm in thickness. This natural texture is a positive characteristic from the point of view of light trapping. By using boron tribromide as a doping agent, degrees of doping ranging from intrinsic to clearly p-doped were obtained, as shown by dark conductivity measurements as a function of temperature. The process, the reactants and the substrate used are of low cost and proved to be adequate for direct poly-Si deposition.

The diodes-based undoped and boron (B) doped ZnO films deposited onto p-Si by sol-gel method using spin coating technique were fabricated. The morphological properties of ZnO films were analyzed by field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) measurements. The results indicated that the surface morphology of the films was affected by the boron incorporation. The diode parameters were determined from the analysis of the measured dark current-voltage curves. The ideality factor of the diodes is higher than unity and was found to be 2.53, 2.36 and 2.17 for the undoped, 0.1% B-doped and 0.3% B-doped ZnO diodes, respectively. The obtained diode parameters like barrier height and ideality factor suggest that B dopant improves rectifying properties of the ZnO diode. The interface states density (Dit) of the diode was determined by conductance-voltage method and Dit values for the undoped, 0.1% B-doped and 0.3% B-doped ZnO diodes were found to be 8.26 × 1011 eV−1 cm−2, 9.75 × 1011 eV−1 cm−2 and 6.61 × 1011 eV−1 cm−2, respectively. The obtained results indicate that the rectifying properties of the diodes-based nanostructure B-doped ZnO can be controlled by boron dopant.

LaFe1-xMnxO3 (x ≤ 0.5) polycrystals have been prepared using solid-state reaction technique and characterized by X-ray diffraction and electrical transport. XRD data suggest orthorhombic structure for both pure and Mn-doped compositions with space group Pbnma. However, unit cell dimensions are found to decrease with increase in Mn concentration. Resistivity data have been fitted with variable range hopping (VRH) model, from which different parameters like density of state at Fermi level N(Ef), hopping energy (Eh), and hopping distance (Rh) were estimated. It was observed that substitution of Mn in the series leads to the increase in conductivity of the samples with conduction being controlled by the disorder-induced localization of charge carriers.

Test structures of memristive devices were prepared by tip-induced oxidation of thin titanium films using atomic force microscope. Electrical measurements of such Ti/TiOx/Ti devices confirmed their memristive behavior and inferred presence of diffusion processes in the TiOx barrier. Consequent Kelvin probe force microscopy studies provided evidence for the diffusion processes as well as for expected electricfield-induced ionic/charge redistribution in the oxide barrier. Time evolution of the surface potential due to the diffusion processes in the TiOx barrier revealed minute-scale (at least) retention times of the devices. The work presents a widely utilizable approach to search for novel oxide materials for perspective memristive applications as well as alternative technology for fabrication of memristive nanodevices in geometry favoring advantageous scanning probe microscopy studies of their in-barrier processes.

The dielectric relaxation and AC conductivity of InP:S single crystal were studied in the frequency range from 100 to 5.25 × 105 Hz and in the temperature range from 296 to 455 K. The dependence of the dielectric constant (ε1) and the dielectric loss (ε2) on both frequency and temperature was investigated. Since no peak was observed on the dielectric loss, we used a method based on the electric modulus to evaluate the activation energy of the dielectric relaxation. Scaling of the electric modulus spectra showed that the charge transport dynamics is independent of temperature. The AC conductivity (σAC) was found to obey the power law: Aωs. Analysis of the AC conductivity data and the frequency exponent showed that the correlated barrier hopping (CBH) model is the dominant mechanism for the AC conduction. The variation of AC conductivity with temperature at different frequencies showed that σAC is a thermally activated process.

The high Al content AlGaN epilayers have been obtained by metalorganic chemical vapor deposition (MOCVD), and the optical property has been investigated by photoluminescence (PL) spectroscopy. Longitudinal-optic (LO) phonon mode has been studied by Raman scattering. Further analysis shows that the edge dislocation is an important factor influencing optical quality of AlGaN epilayers, and it also shows that the correlation between the A1 (LO) polar modes and the edge dislocation is intensive, which may be expected to become a characterization method of the related crystal defects.

In the present work, we report the investigation of passivated silicon nanowires (SiNWs) having an average radius of 3.7 μm, obtained by chemical etching of p-type silicon (p-Si). The surface passivation of the SiNWs was performed through a rapid oxidation conducted under a controlled atmosphere at different temperatures and durations. The morphology of the SiNWs was examined using a scanning electron microscope (SEM) that revealed a wave-like structure of dense and vertically aligned one-dimensional silicon nanostructures. On the other hand, optical and electrical characterizations of the SiNWs were studied using a UV-Vis-NIR spectrometer, the Fourier transform infrared spectroscopy (FTIR) and I-V measurements. The reflectance of SiNWs has been dropped to approximately 2% in comparison to that of bare p-Si. This low reflectance slightly increased after carrying out the rapid thermal annealing. The observed behavior was attributed to the formation of a SiO2 layer, as confirmed by FTIR measurements. Finally, the electrical measurements have shown that the rapid oxidation, at certain conditions, contributes to the improvement of the electrical responses of the SiNWs, which can be of great interest for photovoltaic applications.

This work provides a novel approach for enhanced radiative transitions in silicon microelectronics devices. A process based on hot carrier injection is monitored for the creation of a low dimensions defect layer near the emitter-base interface of bipolar transistors. New energy levels are induced together with a potential barrier. Carrier confinement is correlated with the potential barrier height. The increase of light emission is related to high injection effects in the junction. Results present an advance toward Si-based optoelectronic devices.

The ternary alloys and superlattices (SLs) of cubic rock-salt ScN and YN nitrides have been investigated using the first-principle full potential linear muffin-tin orbital (FPLMTO) method based on local-density approximation (LDA) and generalized gradient approximation (GGA96). The structural parameters as well as the electronic structures of these systems have been calculated and in the light of them, fundamental direct band gaps are expected, instead of the fact that ScN and YN are indirect band gap semiconductors.

Organic photovoltaic (OPV) cells with improved efficiency using thermal annealing-induced nanostructured copper phthalocyanine as a donor layer were fabricated. A power conversion efficiency of 1.47% in the OPV cell with interdigitated CuPc/C60 bulk heterojunction has been obtained under AM 1.5 solar illumination at an intensity of 100 mW/cm2, which is higher than 0.63% of CuPc/C60 planar cell. Through varying the annealing temperature of CuPc films, the influence of interface morphology and crystallinity of CuPc films on the performance of OPV cells was systematically studied. Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and spectrophotometry were used to characterize the CuPc films. The results showed that at an optimal annealing temperature, the crystalline nature and vertical orientation of nanostructured CuPc have been modified, which can facilitate the separation of interfacial electron-hole pairs and charge carrier transport to electrodes.

A nonlinear optical crystal of L-valine was grown from an aqueous solution containing a small amount of phosphoric acid by the slow evaporation method. The grown crystal was characterized by a single crystal X-ray diffraction to determine the unit cell parameters. The powder X-ray diffraction analysis also confirmed the lattice parameters to be a = 9.6687(7) Å, b = 5.2709(4) Å, c = 12.0371(10) Å and β = 90.805(4)°. The results of the Inductively Coupled Plasma Optical Emission Spectrometry (ICPOES) indicate the presence of a small amount of phosphorus in the grown crystal. The Vickers micro hardness test was performed to study the mechanical strength of the crystals. Chemical etching studies were carried out to analyze the dislocation structure. The laser damaged threshold of the grown crystal was measured to be 11.11 GW/cm2 for 10 ns pulse at 1064 nm, which is higher than that of the standard nonlinear optical crystals like KDP. Second harmonic generation of the grown crystals was also 1.44 times that of KDP.

In a recent work we calculated some electronic properties of metal-free phthalocyanine such as band structure, density of states and energy gap. We have also presented some optical properties such as dielectric function, electrical loss function, optical conduction, absorption and refractive index, some of which have never been studied before. Calculations were performed in the framework of density functional theory (DFT), using the full-potential linearized augmented plane wave (FP-LAPW) method. This study presents the electrical gap energy of metal-free phthalocyanine to be Eg = 2.4 eV which is in good agreement with experimental data. A trap energy level is also observed. Optical band gap is about 2.48 eV with an optical trap level at 1.48 eV. In addition, we obtained the static refractive index in the x-, y- and z-directions as n0xx = 2.43, n0yy = 2.06 and n0zz = 2.32. Finally, absorption spectra display the existence of strong absorption bands at the wavelengths of 400 and 800 nm which compare favorably with experimental results.

Series of CoxCr1−x thin films have been evaporated under vacuum onto Si(1 0 0) and glass substrates, x ranging from 0.80 to 0.88; these chemical composition values are provided by modeling Rutherford Backscattering (RBS) spectra using SIMNRA program. Thickness ranges from 17 to 220 nm. Microscopic characterizations of the films have been performed with X-ray diffraction (XRD) measurements. The samples have been annealed for 1 h at 700 °C. All the as deposited samples are polycrystalline, with an hcp structure and show a 〈0 0 0 1〉 preferred orientation. The annealed samples, on the contrary, present hcp and fcc phases. The as deposited films are under a compressive stress while the annealed films are under a tensile stress. Grain sizes increase with chromium content decrease and are higher for the annealed films. Excellent orientations of the CoCr crystallites around the normal to the film plane have been observed, the full width at half maximum (FWHM) ranging from 0.49° to 0.79°.

Amorphous zinc oxide (a-ZnO) thin films were synthesized from RF sputtered Zn thin films. The conversion was performed by processing Zn thin film in ultra high pure water at 95°C in various process times (120–180 min). X-ray spectra revealed the presence of amorphous ZnO in the processed films. The calculated band gap was laid in between 3.25 and 3.2 eV. Non-linear behavior in I-V characteristics was observed for all films. The structural defects of a-ZnO were confirmed with PL and Raman studies. The synthesized films at 180 min were more oxygen deficient.

We have studied the effects of the substrate and the thickness on the structural, electrical and magnetic properties of permalloy thin films Ni81Fe19 (Py). Series of Py thin films were evaporated on four various substrates: glass, kapton, Si(1 0 0) and Si(1 1 1). The thickness ranges from 13 nm to 190 nm. We show that evaporated permalloy on kapton and Si(1 1 1) present a strong ⟨1 1 1⟩ preferred orientation for samples thicker than 85 nm; however, the films grown on glass and Si(1 0 0) present a weak (1 1 1) texture for most of these samples. Generally, the lattice constant for Py/glass, Py/Si(1 0 0) and Py/Si(1 1 1) samples is found to be smaller than the bulk value (abulk), while for the Py/kapton, it is larger than abulk. There is an overall increase of the grain sizes (100 Å–480 Å) with thickness for Py/Si(1 1 1), Py/Si(1 0 0) and Py/glass. For the Py/kapton samples, the grain sizes (about 130 Å) seem to be independent of the thickness. The resistivity, ρ, decreases with increasing thickness for all samples. The highest values of ρ were observed in the Py/kapton thin films, diffusion at the grain boundaries might be in part responsible for these high values. The magnetization easy axis is found to be in the film plane for all samples. For all series, the two thinner films seem to exhibit a perpendicular magnetocrystalline anisotropy. The coercive field, HC//, values range from 1 Oe to 67 Oe. A peak in the HC// vs. t curve is observed for Py/Si while for Py on glass and Py/kapton, HC// seems to be constant. We also observed that for the thicker Py/Si(1 1 1) samples, the coercivity decreases as the grain sizes increase.

The AC and DC electrical properties of sandwich devices fabricated with silicon (Si), porous silicon (PSi) and nanolayers of bromo aluminum phthalocyanine with aluminum electrodes (Al/Si/Al, Al/Si/PSi/Al, Al/Si/BrAlPc/Al and Al/Si/PSi/BrAlPc/Al) were examined over the voltage, frequency and temperature range of 0–11 mV, 102–105 Hz and 303–423 K respectively. Morphology of the samples was studied via scanning electron microscope (SEM) images and X-ray diffraction (XRD) micrographs. Capacitance is practically independent of frequency (f) in the range of 102–104 Hz, whereas it is extremely frequency dependent for f > 104 Hz. Dissipation factor decreased with increasing frequency to a minimum value and increased noticeably thereafter. Capacitance and dissipation factor are almost independent of temperature; capacitance increases with increasing temperature for T > 380 K. The AC electrical behavior of sandwich devices has been shown to be in agreement with the model of Goswami and Goswami. According to our data the Al contact in sandwich devices is of ohmic type and the tunneling mechanism is applicable in explaining the DC conduction process. The Al/Si/PSi/BrAlPc/Al device, compared to other devices, exhibits the highest sensitivity to CO2.

Zinc oxide nanowires were synthesized by a simple chemical method using zinc acetate dihydrate, polyvinylpyrrolidone (PVP) and DI water as precursor, capping and solvent, respectively. Aluminum-doped ZnO nanowires were also synthesized by adding AlCl3 during the growth process. Both types of nanowires were used to fabricate a novel field ionization based gas sensor. The high sensitivity in low pressures, low working voltages, very low recovery time and good selectivity are the main advantages of these fabricated sensors. Electrical characteristics of the fabricated sensors were investigated while being exposed to several gases. Scanning electron microscopy (SEM) was used to analyze the nanowires structures.

Epitaxial magnesium oxide (MgO) thin films prepared on Si(0 0 1) substrates revealed the contraction of its lattice constants along both out-of-plane and in-plane directions. X-ray Diffraction (XRD) verified the epitaxial growth with the relation of MgO(1 0 0) parallel to Si(1 0 0) [cubic on cubic growth] with large lattice misfit of ~22% instead of the relation of MgO(1 1 0) parallel to Si(1 0 0) [45° rotation growth] with lattice mismatch of ~9%. Although the domain epitaxy explaining the cubic on cubic growth is preferred in terms of crystallography, structural stability is not considered in the concept of the domain epitaxy. In order to explain the contraction of lattice constant from point of view of structural stability, ab initio method was used to evaluate all-electron total energy, and optimal lattice constant was estimated with point defects in the MgO structure.

Bismuth zinc niobate (Bi2Zn2/3Nb4/3O7) thin films were deposited by PLD on fused silica substrates at different oxygen pressures. The structural, microwave dielectric, optical and Raman characteristics of these thin films were systematically studied for both the as-deposited films and films annealed at 600 °C. The microwave dielectric constant at a frequency of 10 GHz of the annealed m-BZN films varied from 56 to 71, whereas the dielectric loss tangent varied from 1.8 × 10−4 to 3.5 × 10−4 as a function of deposition pressure. The as-deposited films exhibit refractive index in the range of 2.06–2.15 with an optical absorption edge value between 3.59 and 3.67 eV. The observed Raman scattering in m-BZN thin films was slightly shifted toward the higher frequency which reveals that the local lattice disorder changes whereas the structure remains the same monoclinic in thin film as well as in bulk.

An oxygen plasma treatment was used to prepare Fe-doped TiO2 nanoparticles. The anatase and rutile phases of TiO2 nanoparticles were achieved by an atmospheric pressure chemical vapor deposition method. The nanostructures were doped by Fe atoms to obtain a ferromagnetic nanostructure based on TiO2 nanoparticles. Atomic force microscopy and magnetic force microscopy were used for morphological and magnetic investigation of as-prepared samples. Measurements have confirmed the induced magnetic moment of the structures. Magnetic field-induced wettability of the prepared nanostructures was investigated in dark and under UV and visible light. The results showed a considerable enhancement in the wettability of the structure by applying the magnetic field.