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Regular changes in ferroelectric and pyroelectric properties of P(VDF-TrFE) polymer thin films were observed when the films have a bent-deformation caused by external force. The deformation rate dependence of the remanent polarization, relative dielectric constant and pyroelectric coefficient of the P(VDF-TrFE) thin films were studied. The results demonstrated that there was an increase of ∼12.2% in the remanent polarization of the bent films between the maximum and the minimum bent-deformation rate. Pyroelectric coefficient of the bent P(VDF-TrFE) thin films was also enhanced compared with the flat P(VDF-TrFE) films. P(VDF-TrFE) films can still maintain good performance in ferroelectric and pyroelectric properties under bent deformation, which is meaningful to the potential application in flexible devices.

The effect of the thickness on the dielectric and ferroelectric properties of poly(vinylidene fluoride trifluoroethylene) [P(VDF-TrFE)] copolymer thin films were investigated. The results show that the dielectric constant and tunability increase while the coercive field decreases with increasing film thickness. The film thickness also affects both the reversible and irreversible Raleigh parameters in the ac field dependence of dielectric constant. The observed phenomenon can be explained by the existence of interfacial layers between electrodes and film. No obvious thickness-dependent microstructure and ferroelectric transition temperature was observed.

Electrical properties of poly(vinylidene fluoride trifluoroethylene) [P(VDF-TrFE)] copolymer thin film grown by sol-gel method on flexible polymer substrate were studied. Two types of electrodes, NiFe and Al, were employed to form NiFe/P(VDF-TrFE)/NiFe and Al/P(VDF-TrFE)/Al capacitor structures. The capacitors with NiFe electrodes exhibit higher remnant polarization, lower coercive field, higher dielectric constant and pyroelectric coefficient than the samples with Al electrodes. The improved properties can be attributed to less defects, more charge injection and better interfaces in the NiFe/P(VDF-TrFE)/NiFe capacitor.

Well-crystallized 0.5 mol% Mn doped Pb0.5Sr0.5TiO3 ferroelectric films with remarked ferroelectric properties were prepared by the chemical solution deposition. Optical response of PSMT05 films was investigated by transmittance spectroscopy in the wavelength range from 280 to 1100 nm, which can be simulated by Tauc-Lorentz and Cauchy models and the optical parameters were obtained from the simulations. The fitting of the absorption coefficient with Tauc's law suggests the direct interband transition in PSMT05 films (the band gap is 4.12 eV). Below the band gap, there is a weak band tail absorption region and the band tail energy is about ∼240 meV.

LaNiO 3 (LNO) thin films were deposited by radio frequency magnetron sputtering on n-type Si (100) wafers at room temperature (RT). The as-sputtered LNO thin films were amorphous and had very high RT electrical resistivity even after post-annealing at 800 °C. The amorphous as-sputtered LNO films could be transformed to polycrystalline LNO films in rhombohedral phase by heating at 400 °C in an O 2 atmosphere at pressure ranging from 1.5 to 8.0 MPa. Very low RT resistivity of LNO films were obtained by this high oxygen-pressure processing. The lowest value was as low as 1.09 × 10 − 4 Ω cm by processing at oxygen pressure of 8 MPa. Such preparation of LNO thin films is compatible with the Si-based readout integrated circuits. Highly (100)-oriented perovskite structure of Pb(Zr 0.52 Ti 0.48 )O 3 thin films was formed on this rhombohedral phase LNO, and good ferroelectricity could also be obtained on these HOPP-processed rhombohedral phase LNO films.

The β phase stability in poly(vinylidene fluoride/trifluoroethylene) [P(VDF-TrFE)] thin films was studied below 300 K using X-ray diffraction and polarization-electric-field (P-E) hysteresis loops measurements. On as-grown samples, an irreversible partial order-disorder transformation at T β ∼ 250 K, namely, the β relaxation temperature, was evidenced by the appearance of an additional X-Ray diffraction peak above T β as well as changes on the P-E loops on heating after the first cooling. This order-disorder-like transformation which is attributed to an all-trans order to helical disorder transition is suggested to take place in defect-rich regions like crystal-amorphous interphases and/or crystalline areas with randomly distributed TrFE defect-like units. © 2015 AIP Publishing LLC.

SrTiO3 (STO) thin films with (200) preferential orientation were deposited on p-Si(100) substrates at 700°C by RF magnetron sputtering technique. Their leakage current mechanisms with metal-insulator-semiconductor (MIS) structures were investigated. It was found that the leakage current mechanisms followed the space charge limited current (SCLC) under the low applied electric filed and the Poole-Frenkel emission under the high one. In addition, the resistivity was higher than 1011Ω · cm until the voltage up to 10 V (corresponding to the electric field of 1.54 × 103 kV/cm), indicating that the STO films have good insulation properties.

The TiO2:Ti film was prepared as an alternative of the absorber layer for infrared thermal detectors. The as-deposited film was composed of TiO2 and Ti with a ratio near 5:1. To improve its absorption in infrared region, the film was etched in the diluted H2O2 solution. The etching process made the film porous and reduced the concentration of the free electron in the etched film, which decrease the reflection of the films and subsequently increase their absorption. The maximum absorption of the acid-treated Ti-based film was about 90% for the infrared radiation near 1500 cm−1. The resistivity of the etched films has been derived from four probe method with a two-layer model and from infrared spectrum by simulating it with Drude model. The values of resistivity from the two methods are in good agreement.

The Pb1−xLaxTiO3 (PLT) ferroelectric thin films on Pt/Ti/SiO2/Si(1 0 0) substrates were fabricated by a sol–gel process. The infrared optical properties of PLT thin films with x=0.1, 0.2, 0.25 on platinized silicon Pt(1 1 1)/Ti/SiO2/Si(1 0 0) substrates were studied by infrared spectroscopic ellipsometry (IRSE) technique in the wavelength region from 2.5 to 12.6 μm. The infrared optical constants were obtained by fitting the IRSE data using a classical dielectric function model. The refractive index increases, and the extinction coefficient decreases as wavenumber increases in the measured infrared region. The refractive index of PLT thin films decreases as the La contents increase in the films.

PbZr0.40Ti0.60O3/La x Sr1 − x CoO3 (PZT/LSCO) heterostructures have been grown on Si-based substrates by chemical solution routes. X-ray diffraction analysis showed that PZT on LSCO are polycrystalline with (110) orientation and entirely perovskite phase. The resistance of LSCO is strongly affected by the ratio of La/Sr and the annealing atmosphere for the LSCO thin films. The ferroelectricity of PZT is strongly dependent on LSCO electrode, the P-E hystersis loops of PZT deposited on LSCO which annealed in air is more asymmetry than that annealed in oxygen. At the applied electric field of 300 kV/cm, all PZT films have the resisitivity larger than 1010 Ω · cm. The fatigue resistance is strongly affected by the resistance of the LSCO electrode. The ferroelctric properties are strongly improved by LSCO buffer layer between PZT and Pt bottom electrode.

PbZr0.4Ti0.6O3/La0.5Sr0.5CoO3 heterostructures have been grown on Pt/Ti/SiO2/Si substrates by chemical solution routes. Optical properties of the PbZr0.4Ti0.6O3/La0.5Sr0.5CoO3 heterostructures were studied by infrared spectroscopic ellipsometry (IRSE) in the spectral range of 2.5–12.5 μm. The optical constants of PbZr0.4Ti0.6O3 and La0.5Sr0.5CoO3 thin films were determined by fitting the IRSE data using a classical dielectric model and a Drude dielectric model, respectively. For PbZr0.4Ti0.6O3 thin films, the refractive index decreases and the extinction coefficient increases as the wavelength increases. For La0.5Sr0.5CoO3 thin films, the refractive index and the extinction coefficient increase as the wavelength increases. The absorption coefficient of La0.5Sr0.5CoO3 thin films is greater than 104 cm-1 for the wavelength range of 2.5–12.5 μm. The absorption coefficient of PbZr0.4Ti0.6O3 thin films on a La0.5Sr0.5CoO3/Pt/Ti/SiO2/Si substrate is smaller than that on a Pt/Ti/SiO2/Si substrate by a factor of two.

Barium strontium titanate (Ba 0.9 Sr 0.1 TiO 3 ) ferroelectric thin films have been grown on Pt/Ti/SiO 2 /Si substrates by a modified chemical solution route. X-ray diffraction and Raman spectroscopy measurements show that the films have an excellent crystallinity and crystallize in a tetragonal structure. Field-emission scanning electron microscopy and atomic force microscopy investigations show that the films have a columnar structure with large grains of 80-200 nm in diameter. For an electric field of 320 kV/cm, the remnant polarization and the coercive field are 7.8 μC/cm 2 and 56 kV/cm, respectively. The optical constants (n, k) of the Ba 0.9 Sr 0.1 TiO 3 thin films are obtained by spectroscopic ellipsometry in the spectral range between 0.3 and 1.7 μm, and the band-gap energy is determined to be approximately 3.6 eV.

La0.5Sr0.5CoO3 (LSCO) films have been grown on Si (100) by a metalorganic chemical liquid deposition (MOCLD) technique using lanthanum acetate, strontium acetate and cobalt acetate as the starting materials. Subsequent PbZr0.5Ti0.5O3 (PZT) films were deposited onto LSCO films by a modified sol-gel method. Field-emission scanning electron microscopy and X-ray diffraction analysis show that PZT and LSCO films are polycrystalline and entirely perovskite phase. At an applied electric field of 250 kV/cm, the Pt/PZT/LSCO capacitor shows no polarization fatigue after 3×109 switching cycles and an internal electric field; the remnant polarization Pr and the coercive field Ec are about 22 μC/cm2 and 73 kV/cm, respectively. The dielectric constant of PZT films is 650 at a frequency of 1 kHz.

Lead zirconate titanate PbZr0.50Ti0.50O3 (PZT) ferroelectric thin films were successfully deposited on Pt(1 1 1)/Ti/SiO2/Si substrates by a modified sol–gel method using zirconium nitrate as a substitute for the conventional zirconium alkoxide. The precursor solutions were hydrolyzed with different H2O/Pb ratios. The effect of hydrolysis ratios of the solution on the microstructure for the PZT thin films were investigated via X-ray diffraction (XRD) and atomic force microscopy (AFM) techniques. The XRD results show that the PZT films exhibit (1 1 1)-orientation and the degree of the (1 1 1)-orientation decreases with the increase of hydrolysis ratio. These results indicate that the ferroelectric behavior can be improved by an appropriate choice of H2O/Pb ratio.

The temperature dependence of excess current in the ramp-edge YBa 2 Cu 3 O y /PrBa 2 Cu 3 O y /YBa 2 Cu 3 O y Josephson junctions has been studied. The experimental results indicated that excess current may be caused by Andreev reflection at the SN interfaces of SNS junctions. It was found that the temperature dependence of excess current is the same as that of order parameter at the N side of SN interface. This is in agreement with the prediction of theory. The amplitude of the excess current is the same order as that of critical current.

Highly (100)-oriented LaNiO3 (LNO) films directly on Si substrates were prepared by a simple chemical solution technique using lanthanum nitrate and nickel acetate as the start material sources. Highly (100)-oriented PbZr0.30Ti0.70O3 (PZT30/70) thin film was fabricated subsequently on the LNO-coated Si substrates using a modified sol-gel method. The orientation of the PZT and LNO thin films was characterized by X-ray diffraction (XRD). The resistivity of the LNO thin film at room temperature (300 K) is 7.6×10−4 Ωcm. The remmant polarization (Pr) and coercive field (Ec) of the Pt/PZT/LNO/Si capacitor were 10.5–16.8 μC/cm2 and 20.5–31.6 kV/cm with the variation of electric field (100–200 kV/cm). The values of dielectric constant and dissipation factor of 10 kHz were 700 and 0.019, respectively. After 108 switching cycles, the net-switched polarization values of the capacitor drop to 95, 62, and 37% of their initial values under different electric fields ranging from 100 to 200 kV/cm, respectively.

PbZr0.5Ti0.5O3 thin films have been prepared on Pt (111)/Ti/SiO2/Si substrates by a modified sol–gel technique. The PZT films were annealed layer by layer using a rapid thermal annealing (RTA) method during the spin-coating process. A novel route was used to obtain PZT films with different single-annealed-layer in thickness from the same precursor solution. It is found that the degree of (111) orientation of the films increases with the reduction thickness of single-annealed-layer. As the thickness of single-annealed-layer drops to 40 nm, the film shows a high degree of (111) preferred orientation. The decrease of single-annealed-layer thickness also leads to the increase of the remanent polarization and the dielectric constant.

Bi 3.25 La 0.75 Ti 3 O 12 (BLT) thin film was prepared on quartz substrates using chemical solution deposition. The sign and magnitude of both real and imaginary parts of third-order nonlinear susceptibility χ (3) of the BLT thin film have been determined by the Z-scan technique performed at 800 nm with a femtosecond laser. The nonlinear refractive index coefficient γ and the nonlinear absorption coefficient β of the BLT thin film are − 1.915 × 10 − 12 cm 2 / W and − 6.764 × 10 − 8 m/W, respectively, the real part and imaginary part of the third-order nonlinear susceptibility χ (3) of the BLT thin film are − 5.81 × 10 − 18 m 2 / V 2 and − 1.31 × 10 − 18 m 2 / V 2 , respectively. Both the real and the imaginary parts of the third-order nonlinear susceptibility χ (3) contribute to the nonlinearity of the film. These experimental results show that BLT thin film is a promising material for applications in nonlinear optical devices.

The ferroelectric and dielectric properties of Bi4-xLaxTi3O12 (BLT) and Bi4-xLaxTi2.97V0.03O12 (BLTV) thin films deposited on (111)Pt/Ti/SiO2/Si substrates using a chemical solution method were investigated. The BLTV thin films showed a larger remanent polarization (9.6 μC/cm2) than the BLT thin films (6.5 μC/cm2), while the coercive field for both thin films was nearly the same. The capacitance of the films as a function of a small ac driving field was measured, and the data were processed using Rayleigh’s law. The results show that the Rayleigh constant of the BLT films was smaller than that of the BLTV films, indicating that the defect concentration was lower in the latter case. The superior ferroelectricity of the BLTV films was attributed to a decrease of both the (001) orientation and the defect concentration.

PbZr0.5Ti0.5O3/La0.5Sr0.5CoO3 (PZT/LSCO) heterostructures have been grown directly on (100)Si by chemical solution routes. Field-emission scanning electron microscopy and x-ray diffraction analysis show that PZT and LSCO thin films are polycrystalline and entirely perovskite phase. PZT thin films grown on LSCO thin films showed no preferential orientation and excellent ferroelectricity. The remnant polarization Pr is about 22.8 μC/cm2 and the coercive field Ec is about 95 kV/cm at an applied electric field of 400 kV/cm. The ferroelectric capacitor has been fabricated and showed no polarization fatigue after 3×109 fatigue cycles. The Pt/PZT/LSCO capacitor is suitable for nonvolatile random access memory application.

A highly (100)-oriented metallic LaNiO3 film was prepared directly on a Si substrate by a simple metalorganic decomposition (MOD) technique using lanthanum nitrate and nickel acetate as the starting sources. Subsequent Pb(Zr,Ti)O3 (PZT) thin films deposited on the LaNiO3-coated Si substrate were obtained by a modified sol–gel method. It was found that the PZT thin films began to form a single perovskite phase at a low annealing temperature of 530 °C, and exhibited highly (100) orientation. A ferroelectric capacitor of Pt/Pb(Zr,Ti)O3/LaNiO3/Si annealed at 600 °C displayed a good P-E hysteresis characteristic and was fatigue-free even after 1011 switching cycles.

The authors have investigated the temperature dependence of the ferroelectric, dielectric, and structural properties of 70%Pb(Mg1∕3Nb2∕3)O3–30%PbTiO3 thin films. Two critical temperatures were evidenced. The first one occurring around 410K corresponds to the bulk paraelectric-ferroelectric phase transition and the second one around 200K is rather related to a self-arrangement of small domains into macrodomains in order to minimize elastic energies. A multiscale domainlike structure is induced and the temperature evolution of such complex structure can be revealed through pronounced changes occurring in the nonlinear dielectric susceptibility.

Highly (100)-oriented LaNiO3-δ (LNO) thin film were grown on n-type Si(100) at substrate temperature 200°C with 40% oxygen partial pressure. The as-deposited LNO films are metallic and have a resistivity of ~9×10-4 mΩcm at room temperature (RT) and can be used as the bottom electrode for the fabrication of integrated ferroelectric capacitors on Si. A post-annealing process can decrease the RT resistivity to ~3×10-4 Ωcm at 700°C and yield crack at 800°C.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

La/sub 0.5/Sr/sub 0.5/CoO/sub 3/ /LaNiO/sub 3/ (LSCO/LNO) heterostructures have been grown on Si[100] substrate by chemical solution deposition (MSD) technique. PbZr/sub 0.5/Ti/sub 0.5/O/sub 3/ (PZT) thin films are deposited onto LSCO/LNO heterostructure by a modified sol-gel method. The films were crystallized by rapid thermal annealing (RTA) process. The lowest resistivity (550 /spl mu//spl Omega//spl middot/cm) of LSCO/LNO heterostructures was obtained by annealing at 750/spl deg/C. Field-emission scanning electron microscopy and X-ray diffraction analysis show that LSCO/LNO and PZT thin films are polycrystalline and entirely perovskite phase. The Pt/PZ|T/LSCO/LNO capacitors were fabricated and showed no polarization fatigue after 10/sup 9/ switching cycles. The remnant polarization P/sub r/ and the coercive field E/sub c/ are about 28 /spl mu/C/cm/sup 2/ and 64 kV/cm, respectively. At a high frequency of 1 MHz, the dielectric constant of PZT thin films is 320.