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In this work, VO2 thin films were prepared on three kinds of substrates by the sol-gel dipcoating method followed by heat treatment under vacuum. These thin films were analysed by x-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) techniques. The infrared and ultraviolet-visible spectra of the VO2 thin films were also recorded during heating and cooling between room temperature and 100°C. The experimental results show that VO2 thin films thus prepared exhibit thermally induced reversible phase transition, and the largest changes in transmittance and reflectivity are approximately 58 and 25%, respectively, in the case of vacuum heat treatment at 400°C and silica glass substrates. The refractive index (n) decreases and the absorption coefficient (k) increases when heating these thin films from room temperature to 100°C, and vice versa for cooling. The reasons why the optical constants and infrared absorption spectra change so remarkably are discussed. 相似文献
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A two-step method was proposed to synthesize V2O5 films on planar substrates, i.e., depositing a V2O3 thin film at ∼160°C (by heating a pure sheet of vanadium in a rough vacuum) and then heat-treating it in air at ∼600°C. The
films, made up of nano crystal particles, had good photoluminescence (PL) properties, and the peak was in the position of
about 700 nm. Further, photosensitivity characteristics of these V2O5 thin films were investigated at room temperature. The results show that this film is sensitive to ultraviolet rays, which
indicates good potential application for an ultraviolet photo detector (UVPD). 相似文献
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《Optical Materials》2005,27(2):193-197
The absorption spectrum of spin-coated azo metal thin film showed a comparatively large absorption band in the wavelength region (500–600 nm), which matched with the wavelength of the GaAlInP semiconductor diode laser (630–650 nm). The optical recording performance of the film was investigated. 相似文献
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This paper presents the results of an investigation of a high density magnetic recording technique utilizing a thin film recording head and a transverse mode of recording on thin media. The significant results of this investigation are as follows. 1) Densities as high as 18 500 transitions per inch were experimentally written in a 300-Å thick FeCr medium having an Hc of 70 oersteds. 2) These densities were written with a thin film, vapor-deposited, recording head having a MATED-FILM® structure with a 0.4-mil etched gap. 3) Track widths of 1-mil on 2-mil centers were experimentally achieved. 4) Optical readout of a 0.2-mil wide transition (width of beam) region corresponding to 5000 transitions per inch was achieved using a laser beam and a linear motion transport system under ideal experimental conditions. 5) The magnetic field from the Néel wall separating recording domains was detected using a MATED-FILM Etched Gap head making this a possible readout method. Maximum achieved linear bit densities as a function of recording media coercivities are given. 相似文献
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In this study, we proposed a method to prepare GeO2 by treating porous Ge thin film with thermal annealing in O2 ambient. After annealing, the morphological transformation from porous thin film to an island structure was observed. The crystallization and composition of the porous Ge thin film prepared using different annealing time in O2 ambient were confirmed by X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectra. Initial Ge composition was gradually oxidized to GeO2 with increasing annealing time. Comparing the photoluminescence (PL) results between Ge and GeO2, it was found that the visible photoluminescence originated from the germanium oxide. Photoluminescence measurements obtained at different temperatures exhibited a maximum integrated PL intensity at around 200 K. A possible explanation for this behavior might be the competition between radiative recombination and nonradiative hopping process. 相似文献
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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. 相似文献
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以酒石酸与柠檬酸钠为络合剂,采用化学水浴法(CBD)沉积ZnS薄膜.利用X射线衍射仪(XRD)、X射线能谱仪(EDAX)、扫描电镜(SEM)、紫外-可见分光光度计(UV-Vis)研究ZnS薄膜的结构、组成、形貌及光学性能,利用透射光谱计算ZnS薄膜的光学禁带宽度(Eg).结果表明:ZnS薄膜呈立方相晶体结构,经过300℃熟处理1h的ZnS薄膜原子比为Zn:S=1:0.85,表面均一致密,在可见光区的平均透射率达到80%,光学禁带宽度为3.74ev,适合作为太阳能电池过渡层. 相似文献
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Smart multifunctional materials exhibiting phase transition and tunable optical and/electrical properties provide a new direction towards engineering switchable devices. Specifically, the reversible, tunable and sign switch dielectric constants via external temperature stimuli observed in vanadium dioxide (VO2) make it a candidate of choice for tunable and switchable technologies devices. Here we report new aspect of the metal-insulator transition (MIT) through the sign switch of the static dielectric constant εS of pure VO2. As it is shown, the static dielectric constant showed an abrupt change from positive at T < 70 °C to negative at T > 70 °C. εS > 0 confirms the insulating phase where charges are localized while εS < 0 confirms the metallic phase of VO2 where charges are delocalized. We report for the first time the tunability of the dielectric constant from a negative sign for the static dielectric constant of VO2 thin film rarely found in real physical systems. We also demonstrate the tunability and switchability of the real and imaginary part of the dielectric constant (ε) via external temperature stimuli. More specifically, the real (ε) and Imaginary (ε) showed an abrupt thermal hysteresis which clearly confirms the phase transition. 相似文献
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纳米TiO2薄膜的制备及其紫外光吸收性能的研究 总被引:9,自引:1,他引:9
采用sol-gel法制备TiO2薄膜。用XRD、AFM对其结构及表面形态进行了表征。用UV、SPS测试其光谱吸收、表面光伏特性。结果表明,在高软化温度ITO玻璃上得到比较好的锐钛矿型TiO2薄膜,且具有很强的紫外光吸收特性。随着烧结温度的升高,锐钛矿晶型更加趋于完整,使得紫外吸收曲线的带边蓝移。在紫外光照射下,所制得的薄膜有明显的光伏效应。较之粉体材料,吸收峰更趋向紫外区。为进一步研制新型紫外光传感器提供实验依据。 相似文献
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相变光透射特性具有窗口结构的VO2薄膜 总被引:1,自引:1,他引:0
利用无机溶胶凝胶法制备出具有优良热致相变光学特性的VO2薄膜,通过改变制备过程中的条件,发现在一定的制备参数下,可得到光透射性具有窗口形状的热致相变薄膜,该类薄膜相变前后在600~850nm范围出现显著透光度窗口状态化现象。利用XRD、XPS对相变光学特性具有窗口结构的薄膜和具有典型相变特性的薄膜进行对比分析,结果显示利用无机溶胶-凝胶法得到的薄膜表面没有衬底离子出现,衬底扩散离子主要存在于薄膜和衬底界面之间。通过对引起相变过程中光透射窗口状变化的原因进行讨论,得到薄膜在相变过程中出现透射光谱窗口状的变化是来源于V^3 和衬底扩散离子Na^ 的共同作用。 相似文献
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采用直流及射频磁控溅射结合真空退火的方法成功制备了(001)择优生长的FcPt/B4C多层薄膜并对其结构与磁性能做了初步的表征.结果表明,在每一个FbPt单元层中能得到较好(001)面择优的fet相FbPt合金,并且随着B4C含量的增大,薄膜的有序度提高.高分辨透射电子显微镜及其傅立叶变换表明,FePt层为具有(001)织构的fct相Fe55Pt45合金.样品的M-H曲线显示其垂直膜面方向矫顽力约为302.481kA/m;平行膜面方向矫顽力很小. 相似文献
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采用溶胶-凝胶法,以LiNO3,Co(NO3)2和PAA为主要原料,研究制备LiCoO2薄膜过程中不同实验条件对晶体形成过程及形貌的影响.经偏光显微镜、扫描电镜、原子力显微镜对所形成的薄膜表面进行分析发现聚丙烯酸的含量、Li+离子和Co2+离子的总浓度和配比、烧焙温度及升温速度等均会对薄膜中的成分、纳米化的晶体的形成及表面形貌有着较大的影响.实验表明,最佳烧结温度在600℃左右时有利于LiCoO2晶体的形成. 相似文献