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The bipolar switching properties and electrical conduction mechanism of vanadium oxide thin-film resistive random-access memory (RRAM) devices obtained using a rapid thermal annealing (RTA) process have been investigated in high-resistive status/low-resistive status (HRS/LRS) and are discussed herein. In addition, the resistance switching properties and quality improvement of the vanadium oxide thin-film RRAM devices were measured by x-ray diffraction (XRD) analysis, x-ray photoelectron spectrometry (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and current–voltage (I–V) measurements. The activation energy of the hopping conduction mechanism in the devices was investigated based on Arrhenius plots in HRS and LRS. The hopping conduction distance and activation energy barrier were obtained as 12 nm and 45 meV, respectively. The thermal annealing process is recognized as a candidate method for fabrication of thin-film RRAM devices, being compatible with integrated circuit technology for nonvolatile memory devices.

FeS2 pyrite films are used in a variety of applications including solar cells and, the potential scope for their utilization is increasing as their synthetic methods become more economical while maintaining or enhancing their high light absorption coefficients. The glass substrate temperature dependence on the formation of FeS2 pyrite films was investigated with respect to their optical and physicochemical properties. During the thermochemical spraying process the temperature was varied in the range of 190-290 °C. FeS2 nanocrystalline (40-70 nm) films, formed as a result of atmospheric spraying with glass substrate temperatures above 260 °C, were observed by SEM. Opto-electronic studies revealed that the nanocrystalline films had a direct band gap (1.3-1.6 eV) with a high light absorption coefficient (α > 7 × 104 cm−1 for λ

Nanocrystalline ZnO thin films were prepared by the sol-gel method and annealed at 600 °C by conven- tional (CTA) and rapid thermal annealing (RTA) processes on fluorine-doped tin oxide (FTO)-coated glass substrates for application as the work electrode for a dye-sensitized solar cell (DSSC). ZnO films were crystallized using a con- ventional furnace and the proposed RTA process at anneal- ing rates of 5 °C/min and 600 °C/min, respectively. The ZnO thin films were characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM) analyses. Based on the results, the ZnO thin films crystallized by the RTA process presented better crystallization than films crystallized in a conventional furnace. The ZnO films crystallized by RTA showed higher porosity and surface area than those prepared by CTA. The results show that the short-circuit photocur- rent (Jsc) and open-circuit voltage (Voc) values increased from 4.38 mA/cm 2 and 0.55 V for the DSSC with the CTA- derived ZnO films to 5.88 mA/cm 2 and 0.61 V, respectively, for the DSSC containing the RTA-derived ZnO films.

Bi3.2Gd0.8Ti3O12 (BGTO) thin films were deposited on Pt(111)/Ti/SiO2/Si(100) substrates using the sol-gel method and rapid thermal annealing in an oxygen atmosphere. The effects of annealing temperature (500–800°C) on microstructure and electrical properties of thin films were investigated. X-ray diffraction analysis shows that the BGT thin films have a bismuth-layered perovskite structure with preferred (117) orientation. The intensities of (117) peaks increases with increasing annealing temperature. The leakage current density (J) was 3.69×10−8 A/cm2 at 200 kV/cm. It was found that the leakage current was affected not only by the microstructure but also by the interface between the Pt electrode and BGTO thin films. In the low electric field region, the leakage current was controlled by Poole–Frenkel emission. In addition, the mechanism can be explained by Schottky emission from the Pt electrode in the high electric field region.

The preferred (002) orientation zinc oxide (ZnO) nanocrystalline thin films have been deposited on FTO-coated glass substrates by sol–gel spin-coating technology and rapid thermal annealing for use in dye-sensitized solar cells (DSSC). The effects of preannealing temperature (100 and 300°C) on the microstructure, morphology and optical properties of ZnO thin films were studied. The ZnO thin films were characterized by X-ray diffraction (XRD), scanning electron microscopic (SEM) and Brunauer–Emmett–Teller (BET) analysis. The photoelectric performance of DSSC was studied by I–V curve and the incident photon-to-current conversion efficiency (IPCE), respectively. From the results, the intensities of (002) peaks of ZnO thin films increases with increasing preannealing temperature from 100°C to 300°C. The increase in pore size and surface area of ZnO films crystallized at the increased preannealing temperature contributed to the improvement on the absorption of N3 dye onto the films, the short-circuit photocurrent (J sc) and open-circuit voltage (V oc) of DSSC. The higher efficiency (η) of 2.5% with J sc and V oc of 8.2 mA/cm2 and 0.64 V, respectively, was obtained by the ZnO film preannealed at 300°C.

ZnO-coated TiO2 (ZTO) thin films were deposited on ITO substrates by a sol–gel method for application as the work electrode for dye-sensitized solar cells (DSSCs). The I–V curve and the incident photon-to-current conversion efficiency (IPCE) value of DSSCs for ZTO thin films were studied and compared with single TiO2 films. The results show that the short-circuit photocurrent (J sc) and open-circuit voltage (V oc) values increased from 3.7 mA/cm2 and 0.68 V for the DSSCs with a single TiO2 film to 4.5 mA/cm2 and 0.72 V, respectively, for the DSSCs with a ZTO thin film. It indicated that the DSSCs with a ZTO thin film contributed to provide an inherent energy barrier that suppressed charge recombination significantly. In addition, the higher IPCE value in the ZTO thin film is attributed to the better charge separation by a fast electron transfer process using two semiconductors with different conduction band edges and energy positions.

High-performance pyroelectric infrared detectors have been fabricated using Lithium tantalite (LiTaO3) thin films deposited on Pt(111)/Ti/SiO2/Si(100) substrates by diol-based sol-gel method and rapid thermal annealing (RTA) technique. The dielectric and pyroelectric properties of IR detectors of LiTaO3 thin films crystallized by conventional and RTA processes are investigated. Experimental results reveal that the heating rate will influence strongly on dielectricity and pyroelectricity of LiTaO3 thin films. The voltage responsivities (Rv) measured at 80 Hz increase from 5496 to 8455 V/W and the specific detecivities (D∗) measured at 300 Hz increase from 1.94 × 108 to 2.38 × 108 cmHz1/2/W with an increase of heating rate from 600 to 1800∘C/min. However, the voltage responsivity and the specific detecivity decrease with heating rate in excess of 1800∘C/min. The results show that the LiTaO3 thin film detector with a heating rate of 1800∘C/min exists both the maximums of voltage responsivity and specific detecivity.

Lithium tantalite (LiTaO3) thin films have been deposited on Pt(111)/SiO2/Si(100) substrates by means of sol–gel spin-coating technology. Using a diol-based precursor solution and rapid thermal processing (RTP), highly c-axis oriented LiTaO3 thin films are obtained and the degree of orientation is increased with an increase of the heating rate. By changing the heating rate (600–3000 °C/min) and heating temperature (500–800 °C), the effects of various processing parameters on the growth of films are investigated. With the increase of heating rate, the grain size of LiTaO3 thin films decreases markedly, and the relative dielectric constant (er) increases from 28 up to 45.6. It was found that the dielectric loss factor (cosδ) decreased, and the ferroelectric properties were improved by the increase of heating rate. The figures of merit (Fv and Fm) indicate that the LiTaO3 thin film with a heating rate of 1800 °C/min is suitable for application as a high-performance pyroelectric thin-film detector.

Pb1-xMgxTiO3 (PMT) thin films (x=0–0.08) were deposited onto Pt/SiO2/Si substrates by diol-based sol-gel processing. The influence of various processing methods on the characteristics of the thin films was studied by varying the magnesium contents and heating temperatures (500–800 °C) of the samples. In the present study, the relative dielectric constant (er) of the PMT thin films increased from 25.8 to 91.8 as the magnesium content increased. The coercive field (Ec) and the remanent polarization (Pr) decreased as the magnesium content increased, but the dielectric loss factor (cosδ) and the pyroelectric coefficient (p) increased. The PMT thin films with x=0.06 exhibited the largest figures of merit for voltage responsivity and specific detectivity. These results indicate that the PMT thin film with x=0.06 was most suitable for application to high-performance pyroelectric thin-film detectors.

Well-defined ZnO and Sm-doped nanorods have been successfully fabricated by a low temperature hydrothermal process. The XRD patterns of both compositions with a single diffraction peak (002) show the same wurtzite hexagonal structure. The radius of Sm-ZnO nanorods observed by FE-SEM is smaller than that of pure ZnO, indicating a reduction of the growth rate by the doping of Sm. Ferromagnetism is observed from the results of the magnetization measurements. The increase of the saturation magnetization and decrease of coercivity reveal an association with the increase of oxygen vacancies induced by the doping of Sm in the nanorods.

This paper presents an investigation on the magnetoresistance properties of the polycrystalline manganite oxides, La0.7−xNdxPb0.3MnO3 (x=0.0, 0.1, 0.5 and 0.7). We demonstrate that the magnetoresistance ratio is enhanced with the increase of Nd content due to the suppression of spin scattering in the presence of an applied magnetic field. We find that the magnetoresistance shows an increase with decreasing temperatures at low temperatures. These features have been conventionally attributed to spin-polarized tunneling at grain boundaries. The temperature dependence of the magnetoresistance can be described quite well by an expression of the type a+b/(T+c). At high temperatures the magnetoresistance ratio increases with increasing temperature and the resistivity shows the existence of the variable range hopping with Coulomb effects for x=0.5 and 0.7.

Bi4Ti3.96Nb0.04O12 thin films were successfully deposited on Pt(111)/Ti/SiO2/Si(100) substrates by a sol–gel method and rapid thermal annealing. The effects of Nb-substitution and annealing temperature (500–800°C) on the microstructure and ferroelectric properties of bismuth titanate thin films were investigated. X-ray diffraction analysis reveals that the intensities of (117) peaks are relatively broad and weak at annealing temperatures smaller than 700°C. With the increase of annealing temperature from 500°C to 800°C, the grain size of Bi4Ti3.96Nb0.04O12 thin films increases. The Bi4Ti3.96Nb0.04O12 thin films annealed at 700°C exhibit the highest remanent polarization (2Pr), 36 μC/cm2 and lowest coercive field (2Ec), 110 kV/cm. The improved ferroelectric properties can be attributed to the substitution of Nb5+ to Ti4+ in Bi4Ti3O12 assisting the elimination of defects such as oxygen vacancy and vacancy complexes.

Tantalum doped TiO2 thin films ((TiO2)1−x (Ta2O5)x, x=0, 0.1%, 0.3%, 0.5%, 0.8%) were prepared on ITO-coated substrates by means of the sol–gel method and spin coating technology followed by rapid thermal annealing treatment (RTA). The effects of various processing parameters, including Ta content (x=0–0.8%) and annealing temperature, on the growth and properties of thin films were investigated. Structural characteristics by X-ray diffraction analysis indicated that the doping of Ta2O5 in the TiO2 without change the anatase structure of TiO2 thin films. The optical transmittance of (TiO2)1−x(Ta2O5)x thin films decrease from 50% down to 20% with increasing the Ta2O5 concentrations from x=0.00 to x=0.8%. The absorption coefficient shows energy gap were decreased with increasing Ta2O5 content from 2.932 eV for x=0.00 to 2.717 eV for x=0.8%. Doping TiO2 with Ta2O5 can lower its band gap and shift its optical response to the visible region.

We have prepared Zn1−x Y x O (x=0 and 0.01) tubes to study its structural and photoluminescent properties. A pore wetting process of porous polycarbonate templates with the liquid precursor and following thermal treatment were utilized for preparing the Zn1−x Y x O tube structure. Using the polycarbonate template with pore size of about 2 μm diameter, the Zn1−x Y x O tubes were obtained. Photoluminescence (PL) spectroscopy was used to measure optical emissions from 350 to 650 nm with a He-Cd laser. The results of the PL spectra show that the Zn1−x Y x O tubes have evident emission peaks at the UV (about 380 nm) and visible (around 500 to 650 nm) region. The emission peak at the UV region was slightly shifted to higher wavelengths with increasing Y content. Meanwhile, the green and yellow emission peaks intensity increases as Y content increases. These results are explained by the structure tuning and oxygen deficiency with the introduction of Y.