SrBi2Ta2O9铁电薄膜的三阶非线性光学性能的研究

采用射频磁控溅射法在石英玻璃衬底上制备出均匀透明的SrBi2Ta2O9(SBT)薄膜,根据透射谱计算表明薄膜样品厚度为349nm,线性折射率为3.05.以锁模Nd:YAG激光器作为光源,利用Z-scan技术测定了薄膜的非线性光学性能.结果表明薄膜的非线性折射率n2＝2.56×10-8esu,非线性光吸收系数β＝3.93×10-4 esu,其三阶非线性极化率的实部和虚部分别为:Reχ(3)＝8.29×10-9 esu和Imχ(3)＝1.08×10-9 esu.     

Preparation of plasma poly(1-isoquinolinecarbonitrile) thin film and its ultrafast nonlinear optical property

How to get a uniform, defect-free, and reproducible conjugated polymer thin films is now becoming the main fabrication problem for the practical application of these materials as the fast switches and modulators in opto-electronic devices. In this research, a novel plasma-polymerized 1-isoquinolinecarbonitrile (PPIQCN) thin film was prepared by plasma polymerization under different glow discharge conditions. The effect of the discharge power on the chemical structure and surface compositions of the deposited PPIQCN films was investigated by Fourier transform infrared (FTIR), UV-Visible absorption spectra and X-ray photoelectron spectroscopy (XPS). The results show that a high retention of the aromatic ring structure of the starting monomer in the deposited plasma films is obtained when a low discharge power of 10 W was used during film formation. In the case of higher discharge power of 30 W, more severe monomer molecular fragmentation can be observed, which results in a decrease in the effective conjugation length of PPIQCN film. The morphology characterized by atomic force microscopy (AFM) indicates that a fine, homogenous PPIQCN film could be obtained under a relatively low discharge power. A femtosecond time-resolved optical Kerr effect technique at a wavelength of 820 nm has been applied to investigate the third-order nonlinearity of the plasma PPIQCN film. For the first time, a non-resonant optical Kerr effect and ultrafast response of the PPIQCN film was observed.     

Correlation of viscoelastic properties with solvation of regioregular poly(3-decylthiophene) films

Viscoelastic properties of regioregular poly(3-decylthiophene) films cast on gold electrodes and exposed to acetonitrile/LiClO4 solution were studied using high-frequency acoustic impedance. Values of shear moduli, G = G' + jG', were determined under conditions of potentiodynamic and potentiostatic electrochemical control, as functions of potential (0.0 < E/V < 0.8), temperature (5 < T/ degrees C < 70), and angular frequency (omega = 2pi f; 10 < f/MHz < 110). The effect of potential was small, of temperature was significant, and of frequency was dominant. The principle of time-temperature equivalence was used to construct master relaxation curves. Application of activation, Williams-Landel-Ferry, and Rouse-Zimm models shows the material to be quite different from other thiophene-based conducting polymers, namely, poly(3,4-ethylenedioxythiophene) and regioregular poly(3-hexylthiophene). Detailed exploration of the data reveals novel insights into the compositional origins--notably with regard to solvation--of the shear modulus behavior.     

Ultrafast nonlinear optical effect in CdTe-doped glasses fabricated by the laser evaporation method

The laser evaporation method is an attractive technology to synthesize composite materials. We tried to apply the laser evaporation method on fabrication of CdTe-doped glasses for the first time. CdTe microcrystallites embedded in SiO₂ films were confirmed by transmission electron microscope images. The third-order nonlinear susceptibility χ⁽³⁾ and the decay time τ of CdTe-doped glasses were measured by three-beam forward type degenerate four-wave mixing. The maximum value of χ⁽³⁾ was estimated 4.2 x 10^-7 esu when the absorption coefficient was 6000 cm^-1. From the limitation of pulse duration of 5 ps, τ was not exactly measured but imagined to be shorter than 10 ps, which was much faster than the other semiconductor-doped glasses ever reported. The figure of merit defined as χ^(3)/τ is probably larger than 7.     

钛酸镧铅薄膜的介电、铁电性能研究

采用溶胶－凝胶法在Si衬底上制备了钛酸镧铅薄膜。通过对膜进行XRD、SEM、介电和铁电性能测试，研究了退火条件和掺镧量对薄膜性能的影响，结果发现在600℃下退火1h的PLT薄膜呈现钙钛矿结构；常温下，薄膜的矫顽场和剩余极化强度都随着掺镧量的增加而降低，其介电常数和介质损耗却随掺镧量的增加而增大。     

The effect of Cu doping on optical and surface properties of ZnO thin films fabricated by thermionic vacuum arc (TVA) deposition

Journal of Materials Science: Materials in Electronics - In this work, copper as a dopant was utilized in the ZnO thin film, and furthermore the structural, optical, elemental, and topological...     

Controlling the optical characteristics of CdSx thin film by changing the stoichiometric ratio (x)

Journal of Materials Science: Materials in Electronics - CdSx thin films (x?=?1.0, 0.8, 0.6, 0.4, 0.2) were prepared by the sol–gel spin coating method. The grazing incidence...     

合成方法对聚(3-己基噻吩)立构规整度的影响

采用化学氧化法、格式反应法、GRIM (Grignard Metathesis Method)法和超声辅助GRIM法、合成了不同立构规整度的聚3-己基噻吩(P3HT).用GPC、紫外-可见光谱、红外光谱(FT-IR)和核磁共振谱(1 H-NMR)对P3HT的分子结构和立构规整度进行了表征.结果表明,GRIM法合成的P3...     

Annealing effects on the structural and optical properties of growth ZnO thin films fabricated by pulsed laser deposition (PLD)

Annealed ZnO thin film at 300, 350, 400, 450 and 500 °C in air were deposited on glass substrate by using pulsed laser deposition. The effects of annealing temperature on the structural and optical properties of annealed ZnO thin films by grazing incident X-ray diffraction (GIXRD), transmittance spectra, and photoluminescence (PL) were investigated. The GIXRD reveal the presence of hexagonal wurtzite structure of ZnO with preferred orientation (002). The particle size is calculated using Debye–Scherrer equation and the average grain size were found to be in the range 5.22–10.61 ± 0.01 nm. The transmittance spectra demonstrate highly transparent nature of the films in visible region (>70 %). The calculation of optical band gap energy is found to be in the range 2.95–3.32 ± 0.01 eV. The PL spectra shows that the amorphous film gives a UV emission only and the annealed films produce UV, violet, blue and green emissions this indicates that the point defects increased as the amorphous film was annealed.     

SO1-Gel法硅基PZT铁电薄膜研究

介绍了以硝酸锆、醋本以铅和钛酸四丁酯为原料用溶胶－凝胶（sol-gel）方法在硅衬底上制备Pb（Zr0.53Ti0.47)O3(PZT)铁电膜的工艺流程。对铁电薄膜的表面形貌、晶化程度、界面状态等性质进行了分析,结果表明硅基PZT薄膜形成了良好的钙伏矿结构,并在此基础上实现了制备PZT铁电薄膜的低温改进工艺。     

Fabrication of conducting poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) thin films by ultrasonic spray-assisted mist deposition method

Transparent conducting polymer, poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) thin films were fabricated by a vapor-deposition technique, ultrasonic spray-assisted mist deposition method. The thickness was well controlled from 40 to 600 nm, keeping reasonable conductivity of 300-450 S/cm. The films with thickness less than 180 nm have high (> 80%) transmission over a wide (270-800 nm) spectral region. In addition, formation of ring-dot electrode pattern with a hard-mask was demonstrated, achieving lithography-less patterning. The results encourage that this deposition method is developed as an actual process technology of transparent electrodes in devices.     

Toward understanding the mechanism of nonlinear optical characteristics of PbTe thin film for nano-optical memory

An experimental study is conducted toward understanding the mechanism of nonlinear optical properties of PbTe thin film that were demonstrated potentially usable for nano-optical memory based on super-resolution technology. By way of a real time optical-electrical characterization of a PbTe thin film device, it is found that absorption coefficient decreases with increasing laser power, accompanied by increase in carrier concentration. From z-scan measurements, nonlinear optical coefficient due to a long pulse (1 micros) z-scan is found nearly 3 order of magnitude higher than the one due to a short pulse (30 ps) z-scan when input energy density is relatively comparable. Conceivably, these experimental findings call for a physical model that is able to account for the prevailing role of a thermal contribution within the framework of absorption saturation by band filling. We speculate that the absorption saturation might be enhanced dramatically by making various indirect interband transitions possible via participation of phonons in a photonic excitation process.     

Third-order nonlinear optical responses of nanoparticulate Co3O4 films

Third-order nonlinear optical responses of nanoparticulate Co₃O₄ films, prepared by sputtering and pyrolysis, were investigated. The sputtered Co₃O₄ film showed a large third-order nonlinear susceptibility (|χ⁽³⁾|) of 3.2×10⁻⁸ esu, determined by degenerate four-wave mixing (DFWM). This |χ⁽³⁾| is 7.1 times greater than that of the pyrolyzed Co₃O₄ film, attributable to the greater density and refractive index of the sputtered film. Time-resolved DFWM experiments show a slowly decaying component with a lifetime of approximately 100 ps existing for both films in addition to a fast decaying component. Nonlinear transmission experiments revealed both films exhibiting significant nonlinear absorption. The imaginary part of the susceptibility (Im[χ⁽³⁾]) found for each film was of the same order of magnitude as the |χ⁽³⁾| found by the DFWM method, showing that the major part of the fast decaying component of |χ⁽³⁾| comes from the nonlinear absorption.     

Third-order nonlinear optical properties of sol-gel-derived V(2)O(5), Nb(2)O(5), and Ta(2)O(5) thin films

The third-order nonlinear optical properties of sol-gel-derived V(2)O(5), Nb(2)O(5), and Ta(2)O(5) thin films have been investigated by the third-harmonic-generation method, and the effect of the metal-oxygen bond length on the third-order nonlinear optical susceptibility χ((3)) has been examined. The χ((3)) values of V(2)O(5), Nb(2)O(5), and Ta(2)O(5) thin films were 1.1 × 10(-11), 1.3 × 10(-12), and 6.1 × 10(-13) esu, respectively, which corresponds to an increase in the average bond length I(b) of the order of V-O (I(b) = 0.183 nm), Nb-O (I(b) = 0.200 nm), and Ta-O (I(b) = 0.204 nm). The current and previous results indicate that χ((3)) of these transition metal oxides with the empty d orbitals is dominated mainly by the metal-oxygen bond length rather than the valence of the metal cation. It is predicted on the basis of Lines' model that transition metal oxides with the shortest I(b) exhibit the highest χ((3)), whereas nontransition metal oxides with the longest I(b) exhibit the highest χ((3)).     

Electrical characteristics of poly(3-hexylthiophene) organic thin film transistor with electroplated metal gate electrodes on polyimide

The electroplating of the gate electrode on a flexible polyimide (PI) substrate was successfully applied to the fabrication of inverted-staggered poly(3-hexylthiophene) (P3HT) organic thin film transistors (OTFTs). The Ni gate electrode was electroplated through patterned negative photo-resist (KMPR) masks onto Cu (seed)/Cr (adhesion) layers that had been sputter-deposited on O₂-plasma-treated PI substrates. The electrical measurements of the fabricated OTFTs with the SiO₂ gate insulator indicated non-ideal output characteristics, which are similar to the model of electrical transport by a space-charge limited current (SCLC). The use of a poly(4-vinyl phenol) (PVP) and SiO₂/PVP bilayer gate dielectric produced output characteristics that were closer to the ideal TFT behavior but led to a lower effective mobility and on/off current (I_on/I_off).     

Controlled formation of Ag/poly(methyl-methacrylate) thin films by RAFT technique for optical switcher

The functional group of sulfur was introduced into the PMMA terminus by the reversible addition-fragmentation transfer (RAFT) technique and the PMMA/Ag nanocomposite film was prepared by the in situ synthetic method. The third-order nonlinear optical properties of the material were further investigated by the Z-scan technique. The result shows that the χ⁽³⁾ nonlinearity of the material depend on the doped content of Ag nanoparticles and is obtained to be 6.22 × 10⁻⁹ esu at the content of 2.4 wt%. Furthermore, it is found that the material has the potential application on optical switcher at the content of 0.8 wt%.     

Structure and electrical properties of boron-added (Ba,Sr)TiO3 thin films fabricated by the sol-gel method

Thin films of Ba_xSr_1−xTiO₃ (BST, with x=0.5) were fabricated on a RuO₂/Ru/SiO₂/Si substrate by the spin coating of the multicomponent sol prepared using metal alkoxides. Boron alkoxide was intentionally introduced to establish a better microstructure and to reduce the leakage current. AFM indicated that a crack-free uniform microstructure having a smooth surface was gradually developed with increasing boron content. The relative dielectric permittivity of the 250-nm thick BST thin films fired at 700°C decreased with increasing content of boron, from 420 for the undoped film to 190 for the 10 mol% boron-added film at 1 MHz. This observation was interpreted in terms of a serial capacitance composed of the perovskite BST grain and the interfacial B₂O₃ glassy phase having a low dielectric permittivity. The leakage current density (J) also decreased with the amount of boron added. The leakage current for the applied voltage greater than 1 V showed a linear variation of logJ with E^1/2 at room temperature, suggesting that the interface-controlled Schottky emission was the dominant conduction process for the BST thin films fabricated on the RuO₂ electrode.