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Abstract: A direct-patternable ZnO thin film was prepared by photochemical solution deposition and the electrical properties were improved by the incorporation of graphene. The transmittance of graphene-incorporated ZnO thin films was similar to that of ZnO thin film due to the incorporation of graphene, which slightly decreased the crystallinity of the ZnO thin films. In addition, the resistivity was improved due to the enhanced mobility due to the π-bond nature of the graphene surface. Graphene-incorporated ZnO thin film was direct-patterned through photochemical solution deposition without a photoresist or conventional dry etching process. These results suggest that a micro-patterned system can be simply fabricated at low cost, and the electrical properties of ZnO thin films can be improved by incorporating graphene. [Copyright &y& Elsevier]

Abstract: The sensing properties of direct-patternable TiO2 thin films prepared by photochemical solution deposition were improved by the incorporation of multi-wall carbon nanotubes (MWCNTs). Upon incorporation of the MWCNTs, the crystallinity of the TiO2 thin films containing MWCNTs did not change. However, the electron conductivity was improved due to the π-bond nature of the MWCNT surface. In addition, an increase in the oxidation ratio on the surface of the TiO2 thin films upon MWCNT incorporation caused an increase in surface area. Because of the high electron conductivity and surface area of the MWCNT-incorporated TiO2 sensor, the sensitivity of the sensor was enhanced from 2.19 to 89.2. Direct-patterning of MWCNT-incorporated TiO2 thin films can be performed without a photoresist or etching process. These results suggest that a micro-patterned sensor can be simply fabricated at a low cost and the sensitivity of TiO2 thin films can be improved by incorporating MWCNTs. [Copyright &y& Elsevier]

Abstract: The optical and electrical characteristics of SnO2 composite films with various contents (0, 0.05, 0.1, 0.2, and 0.3at.%) of Pt nanoparticles were evaluated. The Pt nanoparticles were synthesized by a methanol reduction method and their average size was controlled to 3nm using poly(N-vinyl-2-pyrrolidone) as a protecting agent. The lowest resistivity of 2.031×10−2 Ωcm was obtained in the SnO2 film containing 0.2at.% Pt nanoparticles after annealing at 700°C while its average transmittance in the visible region was 85.24%. The enhanced electrical properties were attributed to the increase of the carrier concentration and crystallinity of the films due to donation from Pt nanoparticles as well as the increased annealing temperature. Meanwhile, the slight degradation of the transmittance was due to scattering from the introduction of Pt nanoparticles and the increased crystallite size due to the increase of the annealing temperature to 700°C. Well-defined 20-μm wide direct-patterned composite SnO2 films containing Pt nanoparticles were formed by a simple photochemical metal-organic deposition process involving a photosensitive starting precursor, UV exposure, and removal of the unpatterned area by rinsing with solvent. Based on the results of this study, we suggest that direct-patternable SnO2 films with Pt nanoparticles can be easily applied to transparent electrodes in electrical devices without requiring an expensive and toxic process such as dry etching. [Copyright &y& Elsevier]

Variations in the structural and electrical properties of Bi4Ti3O12 ferroelectric thin films in the Aurivillius family were investigated by substituting Nd3+ for Bi as Bi4-xNdxTi3O12 (x = 0, 0.35, 0.65, and 0.85) using a direct-patternable photochemical metal-organic deposition method. Photoemission spectroscopic and X-ray absorption spectroscopic analyses revealed that as the substitution of Nd3+ for Bi increased until x = 0.65, the orthorhombicity decreased followed by an increase in covalent mixing and centro-symmetry of the Ti-O octahedrons. However, an increase in polarization of the Ti-O octahedron due to Jahn-Teller distortion was observed due to the generation of oxygen vacancies at x = 0.85. [ABSTRACT FROM AUTHOR]

The microstructure and ferroelectric properties of Bi3.25La0.75Ti3O12 films prepared by photochemical metal-organic deposition using photosensitive precursors were characterized. The diffraction intensities showed a distribution similar to Bi3.25La0.75Ti3O12 ceramics, and Pt(111) was found to not influence the growth orientation of Bi3.25La0.75Ti3O12 films. The values of measured remnant polarization and dielectric constant of Bi3.25La0.75Ti3O12 films annealed at 650 and 700°C were 8.7, 16.0 μC/cm2 and 172, 276, respectively. The films remained free of fatigue up to 109 switching cycles. These results suggest the possible application of ferroelectric Bi3.25La0.75Ti3O12 film, relatively easily and without high cost process such as dry etching. [ABSTRACT FROM AUTHOR]

Abstract: The electric and ferroelectric properties of lead zirconate titanate and strontium bismuth tantalate multilayer films prepared using photosensitive starting precursors were characterized. The electric and ferroelectric properties were investigated by characterization of the effect of stacking order of four ferroelectric layers of PZT or SBT in the multilayer films of 4-PZT, PZT/2-SBT/PZT, SBT/2-PZT/SBT, and 4-SBT. The P r value of the 4-SBT multilayer film was relatively small (6μC/cm2) and a two times higher value (12μC/cm2) was obtained with the SBT/2-PZT/SBT multilayer film. The films with SBT layers at the top and bottom showed improved leakage current and fatigue resistance compared to the films with PZT layers at the top and bottom. It was revealed that the defect dipole was reduced at the SBT/Pt interface due to a self-regulation layer such as (Bi2O2)2+ in the SBT film. Also, the bottom layer on the Pt substrate showed a significant influence on the growth orientation of the entire ferroelectric films. [Copyright &y& Elsevier]

Abstract: The electrical and ferroelectric properties of SBT thin films prepared by photochemical metal-organic deposition using photosensitive starting precursors were characterized. Fourier transform infra-red spectroscopic observation showed that a complete removal of organic groups was possible by UV exposure of spin-coated SBT precursor film at room temperature. The values of measured remnant polarization and leakage current density at 400kV/cm were 5.8μC/cm2 and 3.48×10−8 A/cm2 after anneal treatment at 700°C of the UV-exposed SBT precursor film and 10.8μC/cm2 and 6.94×10−8 A/cm2 after anneal treatment at 750°C. The SBT films annealed at 700 and 750°C remained fatigue-free up to 1010 switching cycles. [Copyright &y& Elsevier]

Abstract: The optical and electrical properties were characterized with direct-patternable SnO2 thin film prepared by photochemical metal-organic deposition (PMOD) using photosensitive starting precursors. Fourier transform infrared spectroscopic analysis showed that a complete removal of organic groups was possible by an exposure of spin-coated SnO2 precursor film to UV at room temperature. According to the increase in anneal temperature, i.e., amelioration in the crystallinity and structural homogeneity of SnO2 film, optical transmission and resistivity improved; especially in case of optical transmission, there was also an effect from the decrease in film thickness. Direct-patternable SnO2 film annealed at 800°C showed the values of average transmittance in visible region and resistivity as 92.28% and 1.61×10−2 Ωcm, respectively. [Copyright &y& Elsevier]

Abstract: Direct patterning of ZnO thin film was realized without photoresist and dry etching by photochemical solution deposition. Photosensitive ortho-nitrobenzaldehyde was introduced into the solution precursors as a stabilizer and contributed to form a cross-linked network structure during photochemical reaction. Ag nanoparticles were prepared with uniform size distribution using trisodium citrate as a capping agent to incorporate into ZnO thin film in order to reduce the electrical resistance of the film. The optical and electrical properties of ZnO film with or without Ag nanoparticles after anneal at various temperatures were investigated. The reduction in transmittance with the increase in anneal temperature was observed and also the increase in the electrical resistance was found. The increase in the surface roughness of ZnO film and the decrease of surface oxygen deficiencies were mainly responsible for the decrease in transmittance and the increase in electrical resistance, respectively. [Copyright &y& Elsevier]

Abstract: Ferroelectric properties of direct-patterned PZT(PbZr0.52Ti0.48O3) films with 460μm×460μm size and 510nm thick were analyzed for applying to micro-detecting devices. A photosensitive solution containing ortho-nitrobenzaldehyde was used for the preparation of direct-patterned PZT film. PZT solution was coated on Pt(111)/Ti/SiO2/Si(100) substrate for three times to obtain half-micron thick film and three times of direct-patterning process were repeated to define a pattern on multi-layer PZT film. Through intermediate and final anneal procedure of direct-patterned PZT film, any shrinkage along horizontal direction was not observed within this experimental condition, i.e., the size of the pattern was preserved after annealing, only a thickness reduction was observed after each annealing treatment. Ferroelectric properties of direct-patterned PZT film with 460μm×460μm size and 510nm thick were compared with those of un-patterned conventional PZT film and shown to be almost the same. Through this work, the high potentiality of direct-patternable PZT film for applying to micro-devices without the introduction of physical damages from dry-etching could be confirmed. [Copyright &y& Elsevier]

Direct-patternable lanthanum substituted lead zirconate titanate (PLZT) films were prepared by sol-gel technique using orth-nitrobenzaldehyde as a photosensitive agent. PLZT films with various La concentration were formed on Pt(111)/Ti/SiO 2 /Si(100) substrate for direct-patterning of PLZT films and ferroelectric properties measurement. A well-defined and direct-patterned PLZT film was obtained and the improvement of leakage current density, fatigue resistance and dielectric constant with increased substitution of La in PLZT film were observed especially with 4 mol% La doped PLZT film. From this result, we confirmed that direct-patternable PLZT film is suitable for application in micro device. [ABSTRACT FROM AUTHOR]

The effect of intermediate annealing ambient was investigated for the preparation of thick direct-patternable lead zirconium titanate (PbZrxTi1-xO3; PZT, x=0.52) films using photosensitive stock solution containing diethanolamine (DEA) as stabilizer and ortho-nitrobenzaldehyde (NBAL) as cross-linking agent by metal-organic deposition method. The intermediate anneal was done at 400 °C; for 20 min under air or O2 ambient. The intermediate anneal under O2 brought almost complete removal of organic species, however after anneal under air, carbon and hydrogen atomic species as organic fragment remained in the film. This incomplete removal of organic fragments induced the grain growth of PZT film without influencing from Pt substrate and the formation of micro-voids on film surface during final anneal for the crystallization of PZT film with perovskite structure. The growth direction and surface microstructure of PZT film was revealed to highly affect on leakage, capacitance, fatigue, and piezoelectric properties of PZT film. For PZT film with intermediate anneal under O2, a good piezoelectric property, d33=336 pC/N was obtained with pneumatic loading method, and this film showed 26.2 μC/cm2 of remnant polarization (Pr), 35.6 kV/cm of coercive field (Ec) and well-developed and saturated hysteretic loop. The dielectric constant was obtained as 1795 from the C–V measurement at 1 MHz and 40% of initial polarization value was remained after 109 switching cycles through bipolar square wave of ±10 V at 500 kHz. From the comparison of physical and electrical properties of PZT films prepared with different intermediate anneal ambient such as O2 or air, it can be said that the intermediate annealing condition is very important procedure to control the properties of PZT film for applying it to piezoelectric system devices. [Copyright &y& Elsevier]

Abstract: The ferroelectric properties of lead zirconate titanate (PZT) and lanthanum-doped lead zirconate titanate (PLZT) multilayer films formed by photochemical metal-organic deposition (PMOD) using photosensitive precursors have been characterized. The substitution of La for Pb was reported to induce improved ferroelectric properties, especially fatigue resistance, through the reduction of oxygen vacancies. The relation between La-substitution and the ferroelectric properties was investigated by characterization of the effect of the order of stacking four ferroelectric layers of PZT or PLZT in the multilayer films 4-PZT, PZT/2-PLZT/PZT, PLZT/2-PZT/PLZT, and 4-PLZT. The films with the PLZT layer at the top and bottom showed an improvement in the fatigue resistance. It was revealed that defect dipole such as O vacancy was reduced at the ferroelectric/Pt interface by doping with La. Also, the bottom layer, just on Pt substrate had a significant influence on the surface microstructure and growth orientation of ferroelectric film. [Copyright &y& Elsevier]

Abstract: The electric and ferroelectric properties of UV-irradiated and non-irradiated Bi3.25La0.75Ti3O12 (BLT) films prepared by photochemical metal-organic deposition using photosensitive precursors were characterized. Fourier transform infrared spectroscopy showed that complete removal of organic groups was possible through ultraviolet exposure of the spin-coated BLT precursor films at room temperature. The measured remnant polarization values of UV-irradiated and non-irradiated BLT films after annealing at 700 °C were 16.0 and 10.1 µC/cm2, respectively. The process of UV-irradiation was effective for the enhancement of electric and ferroelectric properties, as well as direct-patterning to fabricate micro-patterned systems without dry etching. [Copyright &y& Elsevier]