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Epitaxial integration of BaTiO3 (BTO)/CoFe2O4 (CFO) multiferroic heterostructure directly on GaN semiconductor was demonstrated using pulsed laser deposition. The domain matching epitaxy mechanism was revealed to be (111)[11¯0] BTO//(111)[11¯0] CFO//(0002)[112¯0] GaN. Spinel CFO thin films with a layer-by-layer growth mode on GaN not only served as the ferrimagnetic functional layer, but also as a buffer layer, inducing an epitaxial growth of perovskite BTO ferroelectric thin films on wurtzite GaN by greatly reducing lattice mismatch at the BTO/GaN interface. The designed BTO/CFO/GaN heterostructure displayed high crystallinity, dense microstructure and good interfacial state. More importantly, good ferroelectric properties for the BTO layer with a remanent polarization of 5.5 μC cm−2 and magnetic properties for the CFO layer with a saturation magnetization of 169 emu cm−3 at room temperature were also demonstrated. Thus, the epitaxial integration of high performance BTO/CFO multiferroic heterostructure with GaN could add more functional degrees of freedom for designing advanced microelectronic devices on a GaN semiconductor platform. [ABSTRACT FROM AUTHOR]

Abstract Co doped SrSnO 3 films (SrSn 1-x Co x O 3 (0 ≤ x ≤ 1. 0), i.e., SSCO) was grown on MgO single crystal substrates by pulsed laser deposition method. Effects of the Co doping content on the crystallinity, microstructure, optical and magnetic properties were examined. For all the films the epitaxial growth along (002) plane was realized, and the lattice constant dropped from 4.065 Å to 3.854 Å with the 'x' value changing from 0 to 1.0. The Co doping promoted the growth of grains and the RMS roughness of the film increased from 3.17 nm to 9.44 nm. With the increase of the Co doping level, the optical transmittance decreased from 95% to 28% at 500 nm, and the band gap varied from 4.51 eV to 3.16 eV. All the films exhibited the room temperature ferromagnetism, and the highest saturated magnetization of 61 emu/cm3 and the coercive force of 0.018 T were realized in the SSCO (x = 1.0) film. Highlights • Co doped SrSnO 3 films were epitaxially grown on MgO single crystal substrates via pulse laser deposition method. • The Co doping level had significant effects on the crystallinity and morphology of the epitaxial films. • The optical band gap of the film was tuned from 4.46 eV to 2.96 eV with different Co doping level. • The room temperature ferromagnetism with the highest M s of 61 emu/cm3 and H c of 0.018 T were realized. [ABSTRACT FROM AUTHOR]

Room-temperature ferromagnetism was obtained in SrSn0.5Co0.5O3 (SSCO) epitaxial film on SrTiO3 substrate by pulsed laser deposition, and the effects of oxygen pressure (PO2) on the microstructure, optical and magnetic properties were examined. An interesting hybrid epitaxial film embedded with polycrystalline SSCO and SrCoOx nanoparticles was observed. The increase of PO2 relaxed the film/substrate compressive strain, promoted the growth of crystallites and reduced the optical band gap (from 2.43 to 1.68 eV). The SSCO film deposited at 0.1 Pa exhibited good ferromagnetism at 100-300 K, while the ferromagnetism in the film with higher and lower oxygen pressure (1 Pa and 10-4 Pa) was weak. [ABSTRACT FROM AUTHOR]

Abstract: ZnO-SDS hybrid thin films were grown on ITO glass using the potentiostatic electrodeposition route from aqueous zinc nitrate solution containing surfactant sodium dodecyle sulfanate (SDS). The electrochemical process of the hybrid films was analyzed by comparing the cyclic voltammetric curve and current–time curve with those of pure ZnO film. Results showed that the addition of a small amount of SDS could decrease the deposition current density, and inhibit the growth of ZnO crystals significantly. The hybrid films electrodeposited at −0.9V for 30min exhibited smooth and platelet-like morphology, with the film thickness of about 110nm. The well-defined ZnO-SDS lamellar structures could be clearly observed, with two interlayer spaces of 35.1 and 30.9Å, respectively. Optical analysis showed that the hybrid films had good optical quality, and exhibited the fundamental absorption edge of ZnO at 380nm. [Copyright &y& Elsevier]

Abstract: The effects of Pt and Cu top electrodes on resistance switching properties were investigated for CuO thin films with Pt/CuO/Pt and Cu/CuO/Pt sandwich structures. Typical unipolar resistance switching (URS) behaviors and two different kinds of resistance changes in the reset process were observed in both structures. When voltages were applied to the film, the low-resistance state (LRS) with relatively low resistance value (<30Ω) was switched to the high-resistance state (HRS), exhibiting normal reset behavior. For LRS with relatively high resistance value (>50Ω), the resistance first decreased then increased to HRS, showing abnormal reset behavior. The former variation of LRS could be ascribed to the decrease in filament size induced by Joule heating, while the latter one could be ascribed to the growth of disconnected filaments induced by high electric fields. This study indicates that the switching modes and the abnormal reset behaviors in CuO thin films are not due to Pt and Cu top electrodes, but the intrinsic properties of CuO film. [Copyright &y& Elsevier]

Abstract: Well crystallined ZnO–eosin Y hybrid thin films were deposited on ITO substrate by two-step cathodic electrodeposition from aqueous mixture of zinc nitrate and esoin Y sodium salt. Effects of the deposition potential on the crystal structure, morphology, and optical properties of the hybrid films were investigated. Results showed that the deposition potential had significant influences on the preferred orientation and the dye loading efficiency of the hybrid film. The nanoporous film with high dye concentration (0.79molL−1) was obtained at −0.8V, while compact films with entrapping eosin Y molecules of relatively lower dye loading (0.28–0.10molL−1) were deposited at more negative potentials. The prototype of dye sensitized solar cells utilizing these hybrid films were fabricated, and their photoelectrochemical properties were characterized. It revealed that the hybrid film with porous nature had better photoelectrochemical property, exhibiting the conversion efficiency of 0.21%, open circuit photovoltage of 0.64V, and short-circuit photocurrent density of 0.67mAcm−2 under AM 1.5 illumination. [Copyright &y& Elsevier]

Abstract: Amorphous Cu2S thin films were deposited on ITO substrate by successive ion layer adsorption and reaction (SILAR) method. Anionic thiosulfatocopper (I) complex ion was used as the single precursor for copper and sulfide ions, and ethylene glycol was used as the solvent. The stoichiometric Cu2S was confirmed by energy dispersive X-ray spectroscopy (EDS). SEM images indicated that the Cu2S films were uniform and composed of nanoparticles. The prepared Cu2S film exhibited high absorption coefficients and wide band gap (higher than 2.55 eV). [Copyright &y& Elsevier]

Abstract: Tantalum pentoxide films were deposited on BK7 glass substrates using oxygen plasma enhanced pulsed laser deposition (OPE-PLD). X-ray diffraction, atomic force microscopy, ultraviolet–visible–near infrared scanning spectrophotometry, and spectroscopic ellipsometry were used to characterize the crystallinity, microscopic morphology and optical properties of films. Results show that the film roughness increased with the increase of oxygen pressure, and decreased with the application of OPE. Meanwhile the use of oxygen plasma in a 2Pa O2 pressure resulted in the transmittance of the thin film of 91.8% at its peak position (the transmittance of bare substrate). Moreover, the root-mean-square roughness as low as 0.736nm, and refractive index of 2.18 at 633nm wavelength, close to the refractive index of bulk Ta2O5 (~2.20 at 633nm wavelength), were obtained. [Copyright &y& Elsevier]

Abstract: Silicon dioxide (SiO2) thin films were deposited on BK7 substrates by pulsed laser deposition (PLD) method using ceramic SiO2 targets (C-SiO2-Ts), which was sintered by solid state sintering. The reason for using C-SiO2-T instead of the silicon target is to reduce the oxygen-deficiency phenomenon in deposited SiO2 thin films. The influence of substrate-temperatures, oxygen-pressures and oxygen-plasma-assistance on the properties of synthesized films was studied. X-ray diffraction, atomic force microscopy, ultraviolet–visible–near-infrared scanning spectrophotometry were used to characterize the crystallinity, morphology and optical properties of deposited films. Results show that the root-mean-square roughness of films increased with the increase of oxygen-pressure, substrate-temperature and with the employment of oxygen-plasma. The transmittance of films increased with the increase of oxygen-pressure and decreased with the increase of substrate-temperature and with the employment of oxygen-plasma. Stoichiometric SiO2 thin film with high optical quality was synthesized at room-temperature and 20Pa oxygen-pressure using C-SiO2-T. [Copyright &y& Elsevier]

Abstract: By introducing different buffer layer, textured or epitaxial La0.5Sr0.5CoO3 (LSCO) thin film can be prepared on Si substrate using pulsed laser deposition (PLD) method. Effects of different buffer layers on growth modes, strain states, and electrical transport properties of LSCO thin films were comparatively investigated. Due to small lattice constant mismatch (1.5%) and similarity of crystalline structure between LSCO and SrTiO3 (STO), the LSCO film on the STO buffer layer is epitaxially grown with layer-by-layer (2D) mode, and the film is under tensile strain. However, owing to large lattice constant mismatch (9%), the LSCO film on the MgO buffer layer is c-axis textured with Stranski–Krastanow (S–K) growth mode, and tensile strain can be relaxed almost fully. Correspondingly, these LSCO films exhibit different electrical transport characteristics, such as electrical resistivity, , etc., which can be ascribed to difference in growth modes and strain states of the LSCO films. [Copyright &y& Elsevier]

Abstract: The amorphous silicon oxide SiO2−x thin films were prepared by the plasma-assisted pulsed laser deposition (PLD) method. X-ray diffraction spectrometry (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), UV-VIS-NIR scanning spectrophotometry and ellipsometry were used to characterize the crystallinity, microscopic morphology and optical properties of obtained thin films. The influences of substrate temperatures, oxygen partial pressures and oxygen plasma assistance on the compositions of silicon oxide (SiO2−x ) thin films were investigated. Results show that the deposited thin films are amorphous and have high surface quality. Stoichiometric silicon dioxide (SiO2) thin film can be obtained at elevated temperature of 200°C in an oxygen plasma-assisted atmosphere. Using normal incidence transmittance, a novel and simple method has been proposed to evaluate the value of x in transparent SiO2−x thin films on a non-absorbing flat substrate. [Copyright &y& Elsevier]

Abstract: ZnO thin films were deposited by pulsed laser deposition on SiO2/Si substrates at high oxygen partial pressures of 2, 20 and 200Pa, respectively. The structure, surface morphology and photoluminescence of the ZnO thin films were investigated. Metal–semiconductor–metal structure prototype detectors were fabricated with ZnO thin films, and their spectral response properties were characterized and discussed. ZnO films deposited at higher oxygen pressure exhibit lower out-of-plane residual compressive stress, larger crystallite size and lower concentration of deep-level defects. Detectors based on ZnO thin films grown at 20 and 200Pa show no response in visible region. The UV response property of ZnO film grown at 20Pa oxygen pressure is better than that at 2 and 200Pa, which may be related to its good crystallinity, smooth surface and less deep-level defects. [Copyright &y& Elsevier]

Abstract: High density TiO2 nanotube film with hexagonal shape and narrow size distribution was fabricated by templating ZnO nanorod array film and sol–gel process. Well-aligned ZnO nanorod array films obtained by aqueous solution method were used as template to synthesize ZnO/TiO2 core–shell structure through sol–gel process. Subsequently, TiO2 nanotube array films survived by removing the ZnO nanorod cores using wet-chemical etching. Polycrystalline anatase TiO2 nanotube films were ∼1.5 μm long and ∼100 nm in inter diameter with a wall thickness of ∼10 nm. [Copyright &y& Elsevier]

To resolve the problem of p-type doping in ZnO, nitrogen and aluminum (N–Al) codoped ZnO films were prepared by the ultrasonic spray pyrolysis (USP) technique. The structural and electrical properties of N–Al codoped ZnO films were investigated. The results demonstrate that the undoped ZnO films exhibit the preferential orientation of (002) plane, while ZnO films show high orientation of (101) plane after codoping with N and Al. The N–Al codoped ZnO films under optimum conditions show p-type conduction, with a low resistivity of 1.7×10-2Ωcm, carrier concentration of 5.09×1018cm-3 and high Hall mobility of 73.6cm2V-1s-1. A conversion from p-type conduction to n-type was observed during the increase of measurement temperature. [Copyright &y& Elsevier]