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Presents information on a study which deposited antiferroelectric lead zirconate thin films by pulsed laser ablation on platinum-coated silicon substrates. Application of ferroelectric thin films; Methodology; Results and discussion; Conclusions.

Abstract: We report low-dimensional fabrication of technologically important giant dielectric material CaCu3Ti4O12 (CCTO) using soft electron beam lithographic technique. Sol–gel precursor solution of CCTO was prepared using inorganic metal nitrates and Ti-isopropoxide. Employing the prepared precursor solution and e-beam lithographically fabricated resist mask CCTO dots with ∼200nm characteristic dimension were fabricated on platinized Si (111) substrate. Phase formation, chemical purity and crystalline nature of fabricated low dimensional structures were investigated with X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS) and selected area electron diffraction (SAED), respectively. Morphological investigations were carried out with the help of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). This kind of solution based fabrication of patterned low-dimensional high dielectric architectures might get potential significance for cost-effective technological applications. [Copyright &y& Elsevier]

Abstract: We report a simple, template free and low-temperature hydrothermal reaction pathway using Cu(II) – thiourea complex (prepared in situ from copper (II) chloride and thiourea as precursors) and citric acid as complexing agent to synthesize two-dimensional hierarchical nano-structures of covellite (CuS). The product was characterized with the help of X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive analysis of X-ray spectroscopy (EDAX) and X-ray photoelectron spectroscopy (XPS). The concentration of citric acid in the hydrothermal precursor solution was seen to have a profound effect on the nanostructure of the product generated. Based on the outcoming product nano-architecture at different concentration of the ionic surfactant in the hydrothermal precursor solution a possible mechanism suited for reaction and further nucleation is also discussed. [Copyright &y& Elsevier]

Abstract: ZnO/Si heterojunctions were fabricated by growing ZnO thin films on p-type Si (100) substrate by pulsed laser deposition without buffer layers. The crystallinity of the heterojunction was analyzed by high resolution X-ray diffraction and atomic force microscopy. The optical quality of the film was analyzed by room temperature (RT) photoluminescence measurements. The high intense band to band emission confirmed the high quality of the ZnO thin films on Si. The electrical properties of the junction were studied by temperature dependent current–voltage measurements and RT capacitance–voltage (C–V) analysis. The charge carrier concentration and the barrier height (BH) were calculated, to be 5.6×1019 cm−3 and 0.6eV respectively from the C–V plot. The BH and ideality factor, calculated using the thermionic emission (TE) model, were found to be highly temperature dependent. We observed a much lower value in Richardson constant, 5.19×10−7 A/cm2 K2 than the theoretical value (32A/cm2 K2) for ZnO. This analysis revealed the existence of a Gaussian distribution (GD) with a standard deviation of σ2 =0.035V. By implementing the GD to the TE, the values of BH and Richardson constant were obtained as 1.3eV and 39.97A/cm2 K2 respectively from the modified Richardson plot. The obtained Richardson constant value is close to the theoretical value for n-ZnO. These high quality heterojunctions can be used for solar cell applications. [Copyright &y& Elsevier]

Abstract: A capillary-enforced template-based method has been applied to fabricate Pb0.76Ca0.24TiO3 (PCT24) nanotubes via filling PCT24 precursor solution, prepared by modified sol–gel method, into nanochannels of anodic aluminum oxide templates. The morphology and structure of as-prepared PCT24 were examined by scanning electron microscopy, transmission electron microscopy (TEM) and X-ray diffraction techniques. The obtained PCT24 nanotubes with diameter of ∼200nm and wall thickness of ∼20nm exhibited a tetragonal perovskite structure. High resolution TEM (HRTEM) analysis confirmed that as-obtained PCT24 nanotubes made up of nanoparticles (5–8nm) which were randomly aligned in the nanotubes. Formation of some solid crystalline PCT24 nanorods, Y-junctions and multi-branches were observed. Interconnections in the pores of template are responsible for the growth of Y-junctions and multi-branches. The possible formation mechanism of PCT24 nanotubes/nanorods was discussed. Ferroelectric hysteresis loops of PCT24 nanotube arrays were measured, showing a room temperature ferroelectric characteristic of as-prepared PCT24 nanotubes. [Copyright &y& Elsevier]

Abstract: Thin films of ZnO, Li doped ZnO (ZLO) and multilayer of ZnO and ZLO (ZnO/ZLO) were grown on silicon and corning glass substrates by pulsed laser deposition technique. Single phase formation and the crystalline qualities of the films were analyzed by X-ray diffraction and Li composition in the film was investigated to be 15wt% by X-ray photoelectron spectroscopy. Raman spectrum reveals the hexagonal wurtzite structure of ZnO, ZLO and ZnO/ZLO multilayer and confirms the single phase formation. Films grown on corning glass shows more than 80% transmittance in the visible region and the optical band gaps were calculated to be 3.245, 3.26 and 3.22eV for ZnO, ZLO and ZnO/ZLO, respectively. An efficient blue emission was observed in all films which were grown on silicon (100) substrate by photoluminescence (PL). PL measurements at different temperatures reveal that the PL emission intensity of ZnO/ZLO multilayer was weakly dependent on temperature as compared to the single layers of ZnO and ZLO and the wavelength of emission was independent of temperature. Our results indicate that ZnO/ZLO multilayer can be used for the fabrication of blue light emitting diodes. [Copyright &y& Elsevier]

Abstract: We report the synthesis and structural characterization of 0.65Pb(Mg1/3Nb2/3)O3–0.35PbTiO3 (PMN-PT) nanotubes prepared by a novel sol–gel template method. X-ray diffraction (XRD) and selected-area electron diffraction (SAED) investigations demonstrated that the postannealed (650 °C for 1 h) PMN-PT nanotubes were polycrystalline with perovskite crystal structure. The field emission scanning electron microscope (FE-SEM) shows that as prepared PMN-PT nanotubes were hollow with diameter to be about 200 nm. High resolution transmission electron microscope (HRTEM) analysis confirmed that the obtained PMN-PT nanotubes made up of nanoparticles (10–20 nm) which were randomly aligned in the nanotubes. Energy-dispersive X-ray spectroscopy (EDX) analysis confirmed the stoichiometric 0.65Pb(Mg1/3Nb2/3)O3–0.35PbTiO3. The possible formation mechanism of PMN-PT nanotubes was proposed at the end. [Copyright &y& Elsevier]

Abstract: A simple, cost-effective and environment-friendly pathway for preparing highly porous matrix of giant dielectric material CaCu3Ti4O12 (CCTO) through combustion of a completely aqueous precursor solution is presented. The pathway yields phase-pure and impurity-less CCTO ceramic at an ultra-low temperature (700°C) and is better than traditional solid-state reaction schemes which fail to produce pure phase at as high temperature as 1000°C (Li, Schwartz, Phys. Rev. B 75, 012104). The porous ceramic matrix on grinding produced CCTO powder having particle size in submicron order with an average size 300nm. On sintering at 1050°C for 5h the powder shows high dielectric constants (>104 at all frequencies from 100Hz to 100kHz) and low loss (with 0.05 as the lowest value) which is suitable for device applications. The reaction pathway is expected to be extended to prepare other multifunctional complex perovskite materials. [Copyright &y& Elsevier]

Abstract: Bi1.5Zn1.0Nb1.5O7/Ba0.6Sr0.4TiO3/Bi1.5Zn1.0Nb1.5O7 tunable multilayer thin film has been fabricated by pulsed laser ablation and characterized. Phase composition and microstructure of multilayer films were characterized by X-ray diffraction, scanning electron microscopy (SEM) and atomic force microscopy (AFM). The film has very smooth surface with RMS roughness of 1.5–2nm and grain size of 100–150nm. Total film thickness has been measure to be 375nm. The BZN thin films at 300K, on Pt(111)/SiO2/Si substrate showed zero-field dielectric constant of 105 and dielectric loss tangent of 0.002 at frequency of 0.1MHz. Thin films annealed at 700°C shows the dielectric tunability of 18% with biasing field 500kV/cm at 0.1MHz. The multilayer thin film shows nonferroelectric behavior at room temperature. The good physical and electrical properties of multilayer thin films make them promising candidate for tunable microwave device applications. [Copyright &y& Elsevier]

Abstract: The dielectric response of pulsed laser ablated Bi1.5Zn1.0Nb1.5O7 (BZN) thin films are investigated within the temperature range of 300–660 K and frequency range of 100 Hz–100 kHz. Thin film exhibited a strong dielectric relaxation behavior. A sharp rise in dielectric constant of BZN thin film at high temperatures is related to disorder in cation and anion lattices. Observed dielectric relaxation implies a redistribution of charges within the unit cell. This phenomenon suggests that the large change in dielectric constant is due to a dynamical rise of dipolar fluctuations in the unit cell. XPS spectra of BZN (A2B2O6O′) cubic pyrochlore, confirm that the relaxation corresponds to the ionic hopping among the A and O′ positions of several local potential minima. Barrier height for hopping is distributed between 0 and 0.94 eV. The O spectrum confirms presence of two types of oxygen in BZN thin film. The disorder in charge neutralized thin film is correlated with XPS spectra. [ABSTRACT FROM AUTHOR]

Abstract: Antiferroelectricity of sol–gel grown pure and La modified PbZrO3 thin films, with a maximum extent of 6 mol%, has been characterized by temperature dependent – hysteresis loops within the applied electric field of 60 MV/m. It has been seen that on extent of La modification electric field induced phase transformation can be altered and at 40 °C its maximum value has been observed at ±38 MV/m on 6 mol% modifications whereas the minimum value is ±22 MV/m on 1 mol%. On La modification the variation of electric field induced phase transformations at 40 °C has been correlated with the temperature of antiferroelectric phase condensation on cooling. The critical electric fields for saturated – hysteresis loops have been defined from field dependent maximum polarizations and their variations on La modification show a similar trend as found in their dielectric phase transition temperatures. [ABSTRACT FROM AUTHOR]

Abstract: The optical properties of Bi2V1−x Mn x O5.5−x {x =0.05, 0.1, 0.15 and 0.2 at.%} thin films fabricated by pulsed laser deposition on platinized silicon substrates were studied in UV–visible spectral region (1.51–4.17eV) using spectroscopic ellipsometry. The optical constants and thicknesses of these films have been obtained by fitting the ellipsometric data (Ψ and Δ) using a multilayer four-phase model system and a relaxed Lorentz oscillator dispersion relation. The surface roughness and film thickness obtained by spectroscopic ellipsometry were found to be consistent with the results obtained by atomic force and scanning electron microscopy. The refractive index measured at 650nm does not show any marginal increase with Mn content. Further, the extinction coefficient does not show much decrease with increasing Mn content. An increase in optical band gap energy from 2.52 to 2.77eV with increasing Mn content from x =0.05 to 0.15 was attributed to the increase in oxygen ion vacancy disorder. [Copyright &y& Elsevier]

Abstract: We fabricated the three-component ferroelectric superlattices consisting of alternating layers of SrTiO3, BaTiO3 and CaTiO3 (SBC) with variable interlayer thickness on Pt(111)/TiO2/SiO2/Si(100) substrates by pulsed laser deposition. The fabrication of superlattice structures was confirmed by the presence of satellite reflections in x-ray diffraction analysis and a periodic concentration of Sr, Ba and Ca throughout the film in depth profile of secondary ion mass spectrometry analysis. The surface morphology evolutions of the films with different thickness of each layer by varying laser pulse shots were investigated by Scanning Electron Microscopy and Atomic Force Microscopy. The (remnant polarization) and (saturation polarization) of SBC superlattice with 10 nm individual layer thickness were found to be around 4.5 μC/cm2 and 27 μC/cm2 respectively. [Copyright &y& Elsevier]

Abstract: Ferroelectric barium strontium titanate, Ba0.6Sr0.4TiO3, (BST40) nanotubes were fabricated by means of sol–gel method utilizing nanochannel porous anodic aluminum oxide (AAO) templates. XRD study confirmed the pure phase perovskite structure of the BST40 nanotubes. TEM analysis confirmed that the nanotubes are composed of nanoparticles in the range of 4–8 nm and the wall thickness of around 12 nm. Y-junctions and multi-branches were also observed in some of the BST40 nanotubes. [Copyright &y& Elsevier]

Abstract: Artificial superlattices of SrTiO3 and BaZrO3 were grown epitaxially with different periodicities on SrRuO3 coated (001) SrTiO3 substrates by pulsed excimer laser ablation. Superlattices were structurally characterized by X-Ray diffraction data. Electrical characterization was done in metal–insulation–metal configuration. Capacitance–voltage measurements showed limited amount of tunability. The DC field induced tunability has been observed to be sensitive to the periodicity of the superlattices, hence the effective strain present in the layers. Hysteretic behaviour in capacitance–voltage () and polarization versus electric field () results from the superlattices also indicate the sensitivity of the interfaces. Interfacial strain is supposed to be the most probable cause for such a behaviour which is also manifested in the variation of dielectric constant with individual layer thicknesses. [Copyright &y& Elsevier]

For the first time, a pulsed laser ablation deposition (PLD) method has been employed for the synthesis of antiferroelectric lead zirconate, PbZrO3, (PZ) nanotubes within the pores of anodic aluminum oxide (AAO) templates. The structure and morphology of fabricated PZ nanotubes were characterized by number of techniques, including scanning electron microscope (SEM), X-ray diffraction (XRD) and transmission electron microscope (TEM)analysis. After postannealing at 650 °C, the PZ nanotubes exhibited a polycrystalline microstructure, and X-ray diffraction studies revealed that they are of an orthorhombic distorted perovskite crystal structure. TEM analysis confirmed that the obtained PZ nanotubes are composed of nanoparticles in the range of 3–7 nm and the thickness of the wall of the nanotubes is around 10 nm. [ABSTRACT FROM AUTHOR]

Abstract: Ferroelectric bismuth vandante, Bi2VO5.5 (BVO) thin films with layered perovskite structure were deposited by pulsed excimer laser ablation technique on (111) Pt/TiO2/SiO2/Si substrates. The polarization hysteresis (P versus E) studies on the BVO thin films at 300K confirmed the remnant polarization (P r) and coercive field (E c) to be 5.6μC/cm2 and 113kV/cm, respectively. The same was corroborated via the capacitance–voltage measurements. The dielectric response and conduction mechanism of BVO thin films under small ac fields were analyzed using impendence spectroscopy. A strong low frequency dielectric dispersion (LFDD) was found to exist in these films, which was ascribed to the presence of the ionized space charge carriers such as oxygen ion vacancies and interfacial polarization. The room temperature dielectric constant and the loss (D) at 100kHz were 233 and 0.07, respectively. The thermal activation energy for the relaxation process of the ionized space charge carriers was 0.85eV. The frequency characteristics of BVO thin films under study showed universal dynamic response that was proposed by Jonscher for the systems associated with quasi-free charges. [Copyright &y& Elsevier]

Electric field (ac and dc) induced complex dielectric properties of 0.7 Pb(Mg1/3Nb2/3)O3–0.3 PbTiO3 (PMN–PT) thin films were studied as a function of frequency at different temperatures. A non-linear behavior of dielectric susceptibility, with respect to the amplitude of the ac drive, was observed at lower temperatures. The magnitude of the dielectric constant measured at 1kHz was increased from 2000 to 6000 with increasing ac signal amplitude from 0.5 to 10kV/cm, while temperature of maximum dielectric constant (Tm) was observed to follow reverse trend at all frequencies. The relaxor nature of PMN–PT thin films was studied in terms of diffused phase transition along with frequency dispersion of temperature of dielectric maximum (Tm). Vogel–Fulcher relationship was used to analyze the frequency dependence of temperature of dielectric maximum (Tm). The dielectric constants (both real and imaginary) of PMN–PT thin films were observed to reduce with the application of external dc field. The external dc bias suppressed the frequency dispersion and increased the ferroelectric stability by increasing the transition temperature (Tm). The disappearance of relaxor nature in PMN–PT (70/30) films was attributed to manifestation of long-range order at higher bias voltage. [Copyright &y& Elsevier]

Dielectric response of 0.7Pb(Mg1/3Nb2/3)O3–0.3PbTiO3 (PMN–PT) thin films deposited by pulsed laser deposition has been studied as a function of frequency over a wide range of temperatures. The films exhibited maximum frequency dispersion in both real and imaginary part of dielectric susceptibility near and below the dielectric transition temperature. The relaxor behavior in the films was confirmed from the diffused phase transition (DP) together with frequency dependent of transition temperature (Tm). The frequency dependence of transition temperature Tm (temperature of the maximum of dielectric constant) was studied in terms of Vogel–Fulcher relation. The dielectric relaxation of PMN–PT thin films was studied at different temperatures using the complex impedance (Z*) and electric modulus (M*) formalism. The shape of complex impedance curve inferred that only one type of dielectric relaxation was involved in the present case. This was attributed to the contribution of bulk grain of the films while the other probable sources, such as grain boundaries, film electrode interfaces were negligible. The films exhibited Debye type dielectric relaxation at temperature sufficiently above the temperature of permittivity maximum (Tm), while a multi-Debye relaxation was observed at lower temperatures (<200 °C), which was confirmed from the broad spectrum of dielectric relaxation. The average relaxation times estimated from Cole–Cole plots varied with temperature according to the V–F relation. [Copyright &y& Elsevier]

Dielectric and DC electrical properties of antiferroelectric lead zirconate and La-doped lead zirconate thin films deposited using a pulsed excimer-laser ablation technique were studied in detail. Increased La dopant concentration in pure lead zirconate thin films reduced the dielectric maximum and Curie temperature. At 9 mol.% of La in pure lead zirconate, the dielectric transition temperature reduced to room temperature. A gradual change from antiferroelectric to paraelectric through ferroelectric phases was observed with the addition of La to pure lead zirconate. The DC electrical properties of pure lead zirconate and the effect of donor addition on leakage current properties were studied. Correlation between the macroscopic changes observed in the charge transport mechanisms, microscopic defect chemistry and charge-carrier trapping phenomenon was examined in detail. [Copyright &y& Elsevier]

Thin films of Ba(Zr0.1Ti0.9)O3 were deposited by pulsed excimer laser ablation technique on Pt substrates. The films were polycrystalline in nature. The room temperature dielectric constant was 450 at a frequency of 100 kHz. Studies indicated that deposition temperature and pressure both have an effect on the crystallinity of the films deposited. The films showed a slightly diffused phase transition in the range of 230–300 K. The ferroelectric nature of the film was confirmed by the polarization hysteresis curves. The saturation and remanent polarization were 13.4 and 5.9 μC/cm2, respectively, with a coercive field of 45 kV/cm. The dispersion in both the real and the imaginary parts of the dielectric constant at low frequencies with increase in temperature was attributed to the space charge contribution to the complex dielectric constant. [Copyright &y& Elsevier]

Abstract: Epitaxial bilayered thin films composed of ferromagnetic La0.6Sr0.4MnO3 and ferroelectric 0.7Pb (Mg1/3Nb2/3)O3–0.3(PbTiO3) were fabricated on LaAlO3 (100) substrates by pulsed laser ablation. Ferroelectric, ferromagnetic and magneto–dielectric characterizations performed earlier indicated the possible existence of strain-mediated magneto–electric coupling in these biferroic heterostructures. In order to investigate their true remnant polarization characteristics, usable in devices, room-temperature polarization versus electric field, positive-up negative-down (PUND) pulse polarization studies and remnant hysteresis measurements were carried out. The PUND and remnant hysteresis measurements revealed the significant contribution of the non-remnant component in the observed polarization hysteresis response of these heterostructures. [Copyright &y& Elsevier]

Examines the deposition of boron nitride thin film on silicon substrate by radiofrequency sputtering in the presence of an electron cyclotron resonance plasma. Identification of structural phases using infrared spectroscopy; Electrical properties of metal-insulator-semiconductor configuration; Determination of the dielectric constant and resistivity.

Examines the deposition of polycrystalline (Pb,La)titanium trioxide thin films by laser ablation on silicon and platinum coated substrates. Dependence of the crystallinity of the films; Appearance of dielectric behavior in terms of varying dielectric permittivity; Sensitivity of the films towards the processing conditions.

Investigates the characteristics of ferroelectric bismuth titanate thin films. Application of the metalorganic solution deposition technique; Use of ferroelectric thin films on microelectronic devices; Fabrication of thin films using bismuth nitrate and titanium isopropoxide.

Examines an excimer laser ablated barium strontium titanate thin films for dynamic random access memory applications. Quality of films deposited near 575 degree Celsius; Measurement of the film dielectric response; Effect of increasing voltage on dielectric breakdown.

Examines the switching characteristics of multi-ion-beam reactive sputter deposited Pb(Zr,Ti)O[sub 3] thin films. Parameters used for the switching characterization; Comparison between films grown with and without low-energy ion bombardment; Determination of the switched charge density.

Examines the deposition of barium titanate (BaTiO[sub 3]) thin films on platinum coated silicon substrates by excimer laser ablation. Crystallinity of the deposited films; Exhibition of the film dielectric constant; Investigation of ferroelectricity by observing polarization hysteresis.

Examines the fabrication of strontium titanate thin films with perovskite structure by rapid thermal annealing treatment. Values for the measured dielectric constant and loss factor; Range of the film resistivity; Decrease leakage current density with increasing film thickness.

Enhances the electrical properties of ferroelectric Pb(Zr,Ti)O[sub 3] thin films using low-energy oxygen ion bombardment. Quantification of the bombardment effect; Dependence of the properties on the ion beam flux and bombarding ion energy; Ratio of the ion and atom between 1.0 and 1.3 and the bombarding energies.

Examines the excimer laser-ablated bismuth titanate thin films. Methods used to study the structure of the films; Deposition rate of bismuth titanate films; Relationship between the process-structure-properties of the bismuth titanate thin films.

Relaxation and conduction mechanisms under small ac fields of laser ablated ZrTiO[sub 4] thin films were analyzed in the light of impedance and modulus spectroscopy. The overall dielectric properties were mainly dominated by a Maxwell–Wagner type of relaxation with grains and the grain boundary two distinct parts of the circuit. Each of these parts was found to follow the universal power law of frequency dispersion. The modulus plot confirmed that the capacitive parts were relatively independent of the frequency and temperature, whereas the impedance and ac conduction studies exhibited significant temperature and frequency dependence. The conduction inside the grains was suggestive of a hopping mechanism through various defect sites whereas the interface barrier potential dictated grain boundary conduction. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Graphene based heat mirror (i.e., graphene/Cu/graphene multilayer coating) was designed and developed to achieve enhanced optical absorption with tunable spectral selectivity. The concept of a heat mirror and a high/low/high refractive index stack was used to develop the graphene/Cu/graphene absorber and the transition from high transmittance to high absorptance was realized on quartz substrates. The thickness of the Cu layer has an important role in creating the destructive interference, for achieving high absorptance and low emittance. The refractive index of the multilayer graphene transferred on Si substrate was studied using phase-modulated spectroscopic ellipsometry. An absorptance of 0.91 and emittance of 0.22 was achieved for the SiO 2 /graphene/Cu/graphene multilayer coating. For the first time, the feasibility of graphene/Cu/graphene multilayer coating for photothermal applications have been demonstrated. [ABSTRACT FROM AUTHOR]

This article presents the announcement of the Asian Meeting on Ferroelectrics (AMF-4), by professor S.B. Krupanidhi, Conference General Chair of AMF-4. The conference will be held in Bangalore city, India, from December 12-15 2003. It will focus on topics related to applications of ferroelectric, piezoelectric, dielectric, pyroelectric properties and microelectromechanical systems to near and far term missions.

Cu 2 SnS 3 thin films were deposited by a facile sol–gel technique followed by annealing. The annealed films were structurally characterized by grazing incidence X-ray diffraction (GIXRD) and transmission electron microscopy (TEM). The crystal structure was found to be tetragonal with crystallite sizes of 2.4–3 nm. Texture coefficient calculations from the GIXRD revealed the preferential orientation of the film along the (112) plane. The morphological investigations of the films were carried out using field emission scanning electron microscopy (FESEM) and the composition using electron dispersive spectroscopy (EDS). The temperature dependent current, voltage characteristics of the Cu 2 SnS 3 /AZnO heterostructure were studied. The log I–log V plot exhibited three regions of different slopes showing linear ohmic behavior and non-linear behavior following the power law. The temperature dependent current voltage characteristics revealed the variation in ideality factor and barrier height with temperature. The Richardson constant was calculated and its deviation from the theoretical value revealed the inhomogeneity of the barrier heights. Transport characteristics were modeled using the thermionic emission model. The Gaussian distribution of barrier heights was applied and from the modified Richardson plot the value of the Richardson constant was found to be 47.18 A cm −2 K −2 . [ABSTRACT FROM AUTHOR]

Thin films of Cu 2 SnS 3 (CTS) were deposited by the facile solution processed sol–gel route followed by a low-temperature annealing. The Cu–Sn-thiourea complex formation was analysed using Fourier Transform Infrared spectrophotometer (FTIR). The various phase transformations and the deposition temperature range for the initial precursor solution was determined using Thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC). X-Ray Diffraction (XRD) studies revealed the tetragonal phase formation of the CTS annealed films. Raman spectroscopy studies further confirmed the tetragonal phase formation and the absence of any deterioratory secondary phases. The morphological investigations and compositional analysis of the films were determined using Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) respectively. Atomic Force Microscopy (AFM) was used to estimate the surface roughness of 1.3 nm. The absorption coefficient was found to be 10 4 cm −1 and bandgap 1.3 eV which qualifies CTS to be a potential candidate for photovoltaic applications. The refractive index, extinction coefficient and relative permittivity of the film were measured by Spectroscopic ellipsometry. Hall effect measurements, indicated the p type nature of the films with a hole concentration of 2 × 10 18 cm −3 , electrical conductivity of 9 S/cm and a hole mobility of 29 cm 2 /V. The properties of CTS as deduced from the current study, present CTS as a potential absorber layer material for thin film solar cells. [ABSTRACT FROM AUTHOR]

Abstract: Ferroelectric c-oriented Bi2VO5.5 (BVO) thin films (thickness ≈300nm) were fabricated by pulsed laser deposition on corning glass substrates. Nonlinear refractive index (n 2) and two photon absorption coefficient (β) were measured by Z-scan technique at 532nm wavelength delivering pulses with 10ns duration. Relatively large values of n 2 =2.05±0.2×10−10 cm2/W and β =9.36±0.3cm/MW were obtained for BVO thin films. Origin of the large optical nonlinearities in BVO thin films was discussed based on bond–orbital theory of transition metal oxides. [Copyright &y& Elsevier]

Abstract: Homogeneous thin films of Sr0.6Ca0.4TiO3 (SCT40) and asymmetric multilayer of SrTiO3 (STO) and CaTiO3 (CTO) were fabricated on Pt/Ti/SiO2/Si substrates by using pulsed laser deposition technique. The electrical behavior of films was observed within a temperature range of 153K–373K. A feeble dielectric peak of SCT40 thin film at 273K is justified as paraelectric to antiferroelectric phase transition. Moreover, the Curie–Weiss temperature, determined from the ε′(T) data above the transition temperature is found to be negative. Using Landau theory, the negative Curie–Weiss temperature is interpreted in terms of an antiferroelectric transition. The asymmetric multilayer exhibits a broad dielectric peak at 273K, and is attributed to interdiffusion at several interfaces of multilayer. The average dielectric constants for homogeneous Sr0.6Ca0.4TiO3 films (∼650) and asymmetric multilayered films (∼350) at room temperature are recognized as a consequence of grain size effect. Small frequency dispersion in the real part of the dielectric constants and relatively low dielectric losses for both cases ensure high quality of the films applicable for next generation integrated devices. [Copyright &y& Elsevier]

Abstract: Inorganic and organic semiconductor devices are generally viewed as distinct and separate technologies. Herein we report a hybrid inorganic–organic light-emitting device employing the use of an air stable polymer, Poly (9,9-dioctylfluorene-alt-benzothiadiazole) as a p-type layer to create a heterojunction, avoiding the use of p-type GaN, which is difficult to grow, being prone to the complex and expensive fabrication techniques that characterises it. I–V characteristics of the GaN–polymer heterojunction fabricated by us exhibits excellent rectification. The luminescence onset voltage is typically about 8–10V. The device emits yellowish white electroluminescence with CIE coordinates (0.42, 0.44). [Copyright &y& Elsevier]

Abstract: Zinc oxide (ZnO) and indium doped ZnO (IZO) thin films with different indium compositions were grown by pulsed laser deposition technique on corning glass substrate. The effect of indium concentration on the structural, morphological, optical and electrical properties of the film was studied. The films were oriented along c-direction with wurtzite structure and highly transparent with an average transmittance of more than 80% in the visible wavelength region. The energy band gap was found to decrease with increasing indium concentration. High transparency makes the films useful as optical windows while the high band gap values support the idea that the film could be a good candidate for optoelectronic devices. The value of resistivity observed to decrease initially with doping concentration and subsequently increases. IZO with 1% of indium showed the lowest resistivity of 2.41×10−2 Ωcm and large transmittance in the visible wavelength region. Especially 1% IZO thin film was observed to be a suitable transparent conducting oxide material to potentially replace indium tin oxide. [Copyright &y& Elsevier]

Abstract: Room-temperature sensing characteristics for H2, ethanol, NH3, H2S and water have been investigated with thick-film sensors based on GaN nanoparticles, prepared by a simple chemical route. In general, GaN nanoparticles exhibit satisfactory sensor properties for these gases and vapors even at room temperature. The sensitivity for ethanol is found to be highest, the sensitivity and recovery times being smallest. Gas sensor properties of GaN seem to be related to intrinsic defects, which act as sorption sites for the gas molecules. [ABSTRACT FROM AUTHOR]

Abstract: Epitaxial heterostructures of La0.6Sr0.4MnO3/0.7Pb(Mg1/3Nb2/3)O3–0.3PbTiO3 were fabricated on LaNiO3 coated LaAlO3 (100) substrates by pulsed laser ablation. Ferromagnetic and ferroelectric hysteresis established their biferroic nature. Dielectric behaviour studied under different magnetic fields over a wide range of temperatures revealed that the capacitance in these heterostructures varies with the applied magnetic field. Appearance of magnetocapacitance and its dependence on temperature and magnetic field strength strongly indicated the possibility of strain mediated magnetoelectric coupling in these heterostructures. [Copyright &y& Elsevier]

Abstract: Bi2V1−x Nb x O5.5 {(x =0, 0.1, 0.2, 0.3, 0.4), (BVN)} thin films were grown by pulsed laser deposition on (111) Pt/TiO2/SiO2/Si and Corning glass substrates and investigated systematically for their microstructural, optical and ac conduction properties. The undoped bismuth vanadate, Bi2VO5.5 (BVO) thin films were highly textured and have been associated with the c-axis oriented grains of the layered perovskite structure, while the Nb doped films consisted of randomly oriented crystallites. The scanning electron microscopy of the films indicates that the grain size increases with increase in Nb content. The optical transmission studies carried out on the samples deposited on Corning glass substrates revealed that these films were nearly 80% transparent in the 400–900nm range and the band gap of Nb doped BVO thin films was slightly higher (3.13eV for x =0.4) than that of the undoped (2.91eV) films. The dielectric constant of the Nb doped films increased with increase in Nb content, while the dielectric loss decreased especially in the 3–100kHz frequency range. At a particular frequency, the conductivity decreased with increase in Nb content in the BVN thin films. In the higher temperature range, the activation energy varied from 0.61eV (x =0.1) to 0.76eV (x =0.4) measured at 100Hz. The frequency analysis of the dielectric and ac conduction properties of these films suggests the conduction process in these films to be via oxygen ion vacancy motion through various defect sites. [Copyright &y& Elsevier]

Abstract: Magnetron sputtering is a promising technique for the growth of oxide materials including ZnO, which allows deposition of films at low temperatures with good electrical properties. The current–voltage (I–V) characteristics of Au Schottky contacts on magnetron sputtered ZnO films have been measured over a temperature range of 278–358K. Both effective barrier height (φ B,eff) and ideality factor (n) are found to be a function of temperature, and this behavior has been interpreted on the basis of a Gaussian distribution of barrier heights due to barrier height inhomogeneities that prevail at the interface. Density of states (DOS) near the Fermi level is determined using a model based on the space charge limited current (SCLC). The dispersion in both real and imaginary parts of the dielectric constant at low frequencies, with increase in temperature is attributed to the space charge effect. Complex impedance plots exhibited two semicircles, which corresponds to bulk grains and the grain boundaries. [Copyright &y& Elsevier]

Abstract: Thin films of ZnO were grown on p-type Si (100) substrates by thermal oxidation. The in situ growth of the metallic Zn films were thermally oxidized at different temperatures ranging from 300 to 500°C to yield ZnO thin films. The structural characterization of the thin films was carried out by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The X-ray diffraction measurements show that the films deposited at 500°C had better crystalline quality than the rest. The electrical transport properties of the ZnO/Si heterojunction were investigated by current–voltage (I–V) and capacitance–voltage (C–V) measurements. The heterojunction exhibited a barrier height, which is consistent with the energy difference between the work functions of Si and ZnO. Complex impedance spectroscopy measurements at temperatures ranging from 50 to 125°C were performed on these heterojunctions. [Copyright &y& Elsevier]

Abstract: Mn x Zn1−x O (x =0.20) thin films were deposited on Pt coated Si substrates using pulsed laser ablation technique. The structural characteristics of the films were investigated by X-ray diffraction (XRD), while the dielectric response of the films was studied as a function of frequency and ambient temperature by employing impedance spectroscopy. It was found that all the films deposited on Pt coated Si substrates had c-axis preferred orientation perpendicular to the substrate, with full width at half maximum (FWHM) of the (002) X-ray reflection line being less than 0.5°. The dc and ac electrical conductivity of Mn-doped ZnO films were investigated as a function of temperature. The ac conductivity, σ ac(ω), varies as σ ac(ω)= Aω s with s in the range 0.4–0.9. The complex impedance plot showed data points lying on a single semicircle, implying the response originated from a single capacitive element corresponding to the bulk grains. The value of the activation energy computed from the Arrhenius plot of both dc and ac conductivities with 1000/T were 0.2eV suggesting hopping conduction mechanism. The optical properties of Zn0.8Mn0.2O thin films were studied in the wavelength range 300–900nm. The data were analyzed in the light of the existing theories and reflected a Burstein–Moss shift in these films. The films show magnetic properties, which are best described by a Curie–Weiss type behavior. [Copyright &y& Elsevier]

Abstract: Experimental study of dc and ac transport properties of CuInSe2/ZnO heterostructure is presented. The current–voltage (I–V) and frequency dependent capacitance (C–f) characteristics of CuInSe2/ZnO heterostructure were investigated in the temperature range 160–393K. The heterostructure showed non-ideal behavior of I–V characteristics with an ideality factor of 3.0 at room temperature. Temperature dependent dc conductivity studies exhibited Arrhenius type behavior and revealed the presence of trap level. The C −2-V plot measured at frequency 50kHz had shown non-linear behavior. An increase in capacitance with temperature was observed. The capacitance–frequency characteristics exhibited a transition between low frequency and the high frequency capacitance. As the temperature was lowered the transition occurred at lower frequencies. The frequency and temperature dependent device capacitance had shown a defect state having activation energy of 108meV. [Copyright &y& Elsevier]

Abstract: Structural and transport properties of CuInSe2/ZnO heterostructure solar cell is investigated. X-ray diffraction pattern of CuInSe2 films exhibited preferred orientation along (112) direction confirming chalcopyrite structure. Structural characterization through scanning electron microscopy revealed dense grains. The electrical properties of the solar cells were investigated using current–voltage (I–V) and capacitance–voltage (C–V) measurements. The dark I–V characteristics revealed that, in the low-field regime, conduction mechanisms follow Ohm''s law and in the high-field region, space charge limited conduction was observed. Frequency-dependent capacitance studies were carried out to characterize the trap properties of the heterostructure. [Copyright &y& Elsevier]

Lanthanum-doped lead titanate (PLT) thin films were identified as the most potential candidates for the pyroelectric and memory applications. PLT thin films were deposited on Pt-coated Si substrates by excimer laser ablation deposition technique. The dielectric response of PLT thin films has been studied over a temperature range of 300–600 K. A universal power law relation was brought into picture to explain the frequency dependence of AC conductivity. The temperature dependence of AC conductivity was analyzed in detail. The activation energy obtained from the temperature dependence of AC conductivity was attributed to the shallow trap-controlled space charge conduction in the bulk of the sample. The impedance analysis combined with modulus spectroscopy was also performed to get insight of the microscopic features like grain, grain boundary and film–electrode interfaces and their effects in the film. The imaginary component of modulus M″ exhibited double peak at high temperatures. Different types of mechanisms were analyzed in detail to explain the dielectric relaxation behavior in the PLT thin films. [Copyright &y& Elsevier]

Abstract: Bi3.99Ti2.97V0.03O12 (BTV) thin films were grown by pulsed laser deposition at substrate temperatures ranging between 650 and 750°C. The structural phase, and orientation of the deposited films were investigated in order to understand the effect of the deposition parameters on the properties of the BTV films. As the substrate temperature was increased to 700°C, the films started showing a tendency of assuming a c-axis preferred orientation, while at lower temperatures polycrystalline films were formed. The Au/BTV/Pt capacitor showed an interesting dependence of the remnant polarization (Pr) as well as dc leakage current values on the growth temperature. The film deposited at 675°C showed a very large 2Pr of 42μCcm-2, which is the largest for BTV thin films among the values reported so far. [Copyright &y& Elsevier]