MR/PVA薄膜的SP和PP偏振存储特性的比较

用两正交偏振光(SP)和两P偏振光(PP)作为记录光(λ=532nm)，记录光的功率均为5mW，用He—Ne激光器632．8nm红光作为读出光，分别得到两种记录条件下甲基红掺杂聚乙烯醇薄膜(MR／PVA)样品的光栅生长曲线．发现用两P偏振光作为记录光时，光栅生长曲线分为快、慢2个过程；两正交偏振光作为记录光时，光栅生长曲线只有一个过程，前者的慢过程和后者过程的响应时间近于相同．     

Laser radiation effects on optical and structural properties of nanostructure CdSe thin film

Cadmium selenide (CdSe) thin films were deposited on a glass substrate using the thermal evaporation method at room temperature. The changes in the optical properties (optical band gap and absorption coefficient) after irradiation by TEA N₂ laser at different energies were measured in the wavelength range 190–800 nm using a spectrophotometer. It was found that the optical band gap is decreased after irradiating the thin films. The samples were characterized using X-ray diffraction (XRD), and the grain size of the CdSe thin film was calculated from XRD data, which was found to be 41.47 nm as-deposited. It was also found that grain size increases with laser exposure. The samples were characterized using a scanning electron microscope and it was found that big clusters were formed after irradiation by TEA N₂ laser.     

ZnSe/SiO2复合薄膜光学常数与荧光光谱的研究

采用溶胶-凝胶工艺与原位生长技术，制备了ZnSe/SiO₂复合薄膜.X射线衍射分 析表明薄膜中ZnSe晶体呈立方闪锌矿结构.X射线荧光分析结果显示薄膜中Zn与Se摩尔比为1 ∶1.01—1∶1.19.利用场发射扫描电子显微镜观察了复合薄膜的表面形貌，结果表明复合薄 膜表面既存在尺寸约为400nm的ZnSe晶粒，也存在尺寸小于100nm的ZnSe晶粒.利用椭偏仪测 量了薄膜椭偏角Ψ，Δ与波长λ的关系，采用Maxwell-Garnett有效介质理论对薄膜的光学 常数、厚度、气孔率、ZnS 关键词： 2复合薄膜')" href="#">ZnSe/SiO₂复合薄膜 光学性质 椭偏光度法 荧光光谱     

基于MEH-PPV/ZnSe纳米复合器件的电致发光特性的研究

以巯基乙酸作为稳定剂在水相中制备了ZnSe纳米晶,用X射线粉末衍射(XRD)和X射线光电子能谱(XPS)对其进行了表征。用表面活性剂将ZnSe纳米晶从水相中转移到有机相中,使其与聚合物MEH-PPV复合作为发光层,制备了多层电致发光器件Glass/ITO/MEH-PPV∶ZnSe/BCP/Alq₃。对ZnSe纳米晶和MEH-PPV薄膜的光致发光谱及其吸收光谱的比较表明ZnSe纳米晶和MEH-PPV之间存在着能量传递,这是导致纳米复合薄膜的光致发光光谱和电致发光光谱存在差异的原因之一。文章对其在光激发和载流子注入条件下的不同发光机制进行了讨论。通过对器件的光电特性进行研究,发现ZnSe纳米晶发光的比例随着外加电压的增加而增加,而且器件的I-V特性基本上符合二极管的特性。     

Study the effect of acetic acid on structural,optical and mechanical properties of PVA/chitosan/MWCNT films

Polyvinyl alcohol (PVA)/chitosan/multiwalled carbon nanotube (MWCNT) films were successfully prepared by using solution-casting method. Structural properties were studied using Fourier transform infrared (FTIR) and X-ray diffraction (XRD) spectroscopies. The effect of acetic acid (AA) concentration on the films optical parameters was studied by using absorbance and transmittance data recorded during ultraviolet-visible (UV–Vis) spectroscopy. The results indicated that increasing the AA concentration in MWCNT-reinforced PVA films caused an increase in their optical capability. We also evaluated mechanical properties such as stress-strain behavior, Young's modulus, tensile strength, elongation at break, etc. Mechanical indices have been modified by introducing carbon nanotubes, even though enhancing the AA concentration meets significant restrictions on higher percentages of AA concentration, which needs to be delicately considered. The porous structure of the films, such as porous pattern, materials’ diameter, and shape was examined by field emission electron microscopy (FESEM). Engineering analyses showed that the films reinforced with MWCNTs exhibited an interconnected homogenous structure in various acid concentrations.     

硒化铅量子点聚乙烯醇薄膜的三阶非线性光学特性

通过湿化学方法制备了具有三阶非线性光学性质的硒化铅/聚乙烯醇复合物薄膜.采用透射电镜和扫描电镜对硒化铅量子点的尺寸和薄膜的形貌进行表征.运用Z扫描方法,研究了薄膜在波长为532nm,脉冲宽度为38ps条件下的三阶非线性光学性质.实验结果表明:合成的硒化铅量子点尺寸在10nm左右,属于强量子受限,制备的薄膜表面粗糙度比较好;薄膜在皮秒脉冲激光作用下呈现负的非线性折射效应和反饱和吸收性质,其三阶非线性极化率χ(3)为3.6×10-11 esu.     

记录薄膜Te—In—Sb光学性质的研究

采用高频溅射方法制成Te-In-Sb系统的非晶态薄膜.系统的研究了不同组分薄膜的透射、反射谱,及其在结晶过程中的变化.用透射电镜研究了Te-In-Sb薄膜的结构和晶化过程.分析了组分对薄膜的吸收系数、介电常数、光学能隙等光学性质的影响.并由此综合评价了Te-In—Sb系统中比较适合作为光盘介质的组成.     

In掺杂氮化亚铜薄膜的电学、光学和结构特性研究

采用射频磁控溅射方法, 在低功率和低温条件下利用纯氮气作为反应溅射气体制 备出不同In含量的三元氮化物Cu_xIn_yN薄膜. 研究发现In掺杂浓度对薄膜微结构、形貌、表面化学态以及光学特性有灵敏的调节作用. 光电子峰、俄歇峰、俄歇参数的化学位移变化从不同角度揭示了不同含量In掺杂引 起的原子结合情况的变化. XPS结果显示In含量小于8.2 at.%的样品形成了Cu-In-N键. 对In含量为4.6 at.%的样品进行XRD和TEM结构测试, 实验结果肯定了In原子填充到Cu₃N的反ReO₃结构的体心位置. 并且当In含量增至10.7 at.%时, 薄膜生长的择优取向从之前占主导地位的(001)方向转变为(111)方向. 此外, 随着In含量的增加, 薄膜的R-T曲线从指数形式变为线性. 当In含量为47.9 at.%时, 薄膜趋于大温区恒电阻率材料, 电阻温度系数TCR仅为-6/10000. 光谱测量结果显示In摻杂使得氮化亚铜掺杂薄膜的光学帯隙从间接帯隙变为直接帯隙. 由于Burstein-Moss效应, 帯隙发生蓝移, 从1.02 eV 到2.51 eV, 实现了帯隙连续可调. 关键词： 三元氮化物 薄膜 光学特性 氮化亚铜     

Effect of cycle numbers on the structural,linear and nonlinear optical properties in Fe2O3 thin films deposited by SILAR method

Fe₂O₃ thin films were deposited by Successive Ionic Layer Adsorption and Reaction (SILAR) method onto glass substrates at different cycle numbers to investigate structural, linear and nonlinear optical properties. X-Ray Diffraction (XRD) analysis revealed that the Fe₂O₃ thin films have a non-crystalline nature. The morphological properties of the films were investigated by Field Emission-Scanning Electron Microscopy (FE-SEM) and the results show that the films’ surfaces are porous. The linear and nonlinear optical parameters were evaluated and analyzed by using transmittance and absorbance measurements. For these measurements, UV–Vis spectroscopy at room temperature was used. The refractive index values were calculated in the range of 1.45–3.23 for visible region (400–700 nm). Obtained results reveal that direct optical band gap changed between 2.62 and 2.68 eV and indirect optical band gap changed between 1.67 and 1.77 eV. Additionally, optical electronegativity, optical dielectric constants, surface and volume energy loss functions, nonlinear refractive index, linear optical susceptibility, third-order nonlinear optical susceptibility, optical and electrical conductivity, and loss tangent values were calculated and discussed in detail. It was found that each parameter studied is dependent on the cycle numbers. Also, it can be stated that Fe₂O₃ thin films are promising candidate for solar cells and optoelectronic device technology.     

Microstructure and optical properties of nitrogen-doped ZnO film

The nitrogen doping of ZnO film deposited by the magnetron sputtering method is subsequently realized by the hydrothermal synthesis method.The nitrogen-doped ZnO film is preferably(002) oriented.With the increase of hexamethylenetetramine(HMT) solution concentration,the average grain size of the film along the 002 direction almost immediately decreases and then monotonously increases,conversely,the lattice strain first increases and then decreases.The structural evolution of the film surface from compact and even to sparse and rough is attributed to the enhanced nitrogen doping content in the hydrothermal process.The transmission and photoluminescence properties of the film are closely related to grain size,lattice strain,and nitrogen-related defect arising from the enhanced nitrogen doping content with HMT concentration increasing.     

CO2 sensing properties of semiconducting copper oxide and spinel ferrite nanocomposite thin film

A new active layer for CO₂ sensing based on semiconducting CuO-Cu_xFe_3−xO₄ (with 0 ≤ x ≤ 1) nanocomposite was prepared by radiofrequency sputtering from a delafossite CuFeO₂ target using a specific in situ reduction method followed by post annealing treatment in air. The tenorite-spinel ferrite nanocomposite layer was deposited on a simplified test device and the response in a carbon dioxide atmosphere was measured by varying the concentration up to 5000 ppm, at different working temperatures (130-475 °C) and frequencies (0.5-250 kHz). The results showed a high response of 50% (Rair/RCO₂=1.9) at 250 °C and 700 Hz for a CO₂ concentration of 5000 ppm.     

Effect of electron beam irradiation on the structural,thermal and optical properties of poly(vinyl alcohol) thin film

Poly(vinyl alcohol) (PVA) polymer was prepared using the casting technique. The obtained PVA thin films have been irradiated with electron beam doses ranging from 20 to 300 kGy. The resultant effect of electron beam irradiation on the structural properties of PVA has been investigated using X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR), while the thermal properties have been investigated using thermo-gravimetric analysis and differential thermal analysis (DTA). The onset temperature of decomposition T ₀ and activation energy of thermal decomposition E _a were calculated, results indicate that the PVA thin film decomposes in one main weight loss stage. Also, the electron beam irradiation in dose range 95–210 kGy led to a more compact structure of the PVA polymer, which resulted in an improvement in its thermal stability with an increase in the activation energy of thermal decomposition. The variation of transition temperatures with electron beam dose has been determined using DTA. The PVA thermograms were characterized by the appearance of an endothermic peak due to melting. In addition, the transmission of the PVA samples and any color changes were studied. The color intensity Δ E was greatly increased with increasing electron beam dose, and was accompanied by a significant increase in the blue color component.     

Influence of air annealing on the structural, morphological, optical and electrical properties of chemically deposited ZnSe thin films

Zinc selenide nanocrystalline thin films are grown onto amorphous glass substrate from an aqueous alkaline medium, using chemical bath deposition (CBD) method. The ZnSe thin films are annealed in air for 4 h at various temperatures and characterized by structural, morphological, optical and electrical properties. The as-deposited ZnSe film grew with nanocrystalline cubic phase alongwith some amorphous phase present in it. After annealing metastable nanocrystalline cubic phase was transformed into stable polycrystalline hexagonal phase with partial conversion of ZnSe into ZnO. The optical band gap, E_g, of as-deposited film is 2.85 eV and electrical resistivity of the order of 10⁶-10⁷ Ω cm. Depending upon annealing temperature, decrease up to 0.15 eV and 10² Ω cm were observed in the optical band gap, E_g, and electrical resistivity, respectively.     

Physical properties of ZnSe thin films deposited on glass and silicon substrates

ZnSe thin films were deposited onto Corning glass and silicon substrates using thermal evaporation. The samples were prepared at different substrate temperatures. The thin films’ surface chemical composition was determined through Auger electron spectroscopy (AES). AES signals corresponding to Zn and Se were only detected in AES spectra. The samples’ crystallographic structure was studied through X-ray diffraction. The material crystallised in the cubic structure with preferential orientation (111). Optical properties of the ZnSe films were studied over two energy ranges via electron energy loss spectroscopy (10–90 eV) and spectral transmittance measurements (0.4–4 eV). In both cases, the spectral variation of the refractive index and the absorption coefficient were determined by fitting the experimental results with well-established theoretical models. Experimental values for the material’s gap were also found, and photoconductivity (PC) measurements were carried out. Transitions between bands, usually labelled Γ^V₈ → Γ^C₆ and Γ^V₇ → Γ^C₆, were found in the optical and PC responses. A wide spectral photoconductive response between 300 and 850 nm was found in the ZnSe/Si samples prepared at 250 °C substrate temperature.     

Ultrasonic-assisted synthesis of polyvinyl alcohol/phytic acid polymer film and its thermal stability,mechanical properties and surface resistivity

In this paper, polyvinyl alcohol/phytic acid polymer (PVA/PA polymer) was synthesized through esterification reaction of PVA and PA in the case of acidity and ultrasound irradiation and characterized, and PVA/PA polymer film was prepared by PVA/PA polymer and characterized, and the influence of dosage of PA on the thermal stability, mechanical properties and surface resistivity of PVA/PA polymer film were researched, and the influence of sonication time on the mechanical properties of PVA/PA polymer film was investigated. Based on those, it was concluded that the hydroxyl group on the chain of PVA and the phosphonic group on PA were connected together in the form of phosphonate bond, and the hydroxyl group on the chain of PVA were connected together in the form of ether bond after the intermolecular dehydration; in the meantime, it was also confirmed that PVA/PA polymer film prepared from 1.20 mL of PA not only had the high thermal stability and favorable ductility but also the low surface resistivity in comparison with PVA/PA polymer film with 0.00 mL of PA, and the ductility of PVA/PA polymer film was very sensitive to the sonication time.     

Observation of simultaneous reverse saturation absorption and saturation absorption in silver nanoparticles incorporated into europium oxide thin film

In this work, nano silver clusters incorporated into europium oxide thin films at a level of 3.8% and 12.5% have been prepared by a vacuum evaporation method on glass and silicon substrates. Samples were investigated by X-ray fluorescence, X-ray diffraction, and linear and nonlinear optical absorption methods. The X-ray diffraction reveals that the Eu oxide of these samples remains amorphous after pre-annealing at 400 °C. The linear optical absorption of the samples shows surface plasmon resonance (SPR) phenomena, which varies with the Ag content of the samples. The optical nonlinear absorption properties of the prepared films were investigated using an open Z-scan technique with cw laser at wavelengths 476 nm and 514 nm. A changeover from reverse saturation absorption (RSA) to saturation absorption (SA) was observed. RSA is attributed to interband transition via two photon absorption. SA is attributed to plasmon bleach.     

Improvement in mechanical and optical properties of vapour chopped vacuum evaporated PANI/PMMA composite thin film

PANI/PMMA composite was synthesized by emulsion polymerization pathway and the composite thin film was obtained by vacuum evaporation. The effect of vapour chopping and varying PMMA concentration was also studied. The FTIR spectra showed that the PANI/PMMA composite thin film deposited as a short chain oligomers. Increase in transmittance and decrease in refractive index was obtained with increasing concentration of PMMA, which further increased the adhesion and decreased intrinsic stress. The vapour chopping improved its optical as well as mechanical properties and produced smoother surface morphology. Increase of PMMA made the film more amorphous and does not change its band gap.     

Effects of annealing on structural,optical and electrical properties of Al-doped ZnO thin films

Transparent conducting oxide (TCO) thin films such as SnO2, In2O3, and Cd2SnO4, have been used extensively as sensor devices, surface acoustic wave devices, coating to heat glass windows and transparent electrodes for solid state display devices, solar cells[1,2] because of their high optical transparency in the visible range, infrared reflec-tance and low d.c. resistivity. Although SnO2 film was developed early, nowadays Sn-doped In2O3 (ITO) films are the predominant TCO thin film in …     

Influence of different stabilizers on the optical and nonlinear optical properties of CdTe nanoparticles

CdTe semiconductor nanocrystals were synthesized with three different stabilizers: Mercaptoacetic Acid (MAA), Mercaptopropionic Acid (MPA) and 2-Mercaptoethanol (ME) at pH ≈ 11.2 by wet chemical route using potassium tellurite and cadmium chloride as starting materials. The effect of capping agent on the preparation of these samples was evaluated using UV-Visible absorption and photoluminescence analysis. With the same reaction time but with different stabilizers, nanocrystals of different diameters were obtained. The average full width at half maximum of the photoluminescence spectra was about 69 nm which indicates that the monodispersity was quite good. The particle size was calculated by Debye-Scherrer equation from XRD data. Further characterization studies such as FT-IR and optical nonlinearity studies on the samples were carried out and the results are discussed.     

氢致LaMg2Ni合金薄膜的光电性能变化

采用电子束蒸发法沉积LaNi/Mg多层膜,再于350℃真空退火合金化的方法制备了厚度为375nm的LaMg₂Ni合金薄膜.在吸、放氢过程中,该合金薄膜能够在高反射的金属态和透明的半导体态之间可逆地转变.在可见光波长范围内的平均透射率和电阻率在反射态和透明态之间的对比度大于10⁴.利用扫描电子显微镜和原子力显微镜观察了吸放氢前后薄膜的表面及剖面形貌.结果表明,在氢化过程中薄膜表面的平整性降低且不可恢复,是脱氢态中出现低反射现象的主要原因. 关键词： 薄膜 光电性能 氢 形貌