Spectral remittances of chiral sculptured zirconia thin films in non-axial propagation

The transmission and reflection spectra from a right-handed chiral sculptured zirconia thin film are calculated using the piecewise homogeneity approximation method and the Bruggeman homogenization formalism and by considering that the dispersion of the dielectric function happens in a non-axial propagation state. First and second Bragg peaks were observed in cross-polarized reflectances and it became clear that increasing the azimuthal angle affects the spectra of the linearly polarized state significantly. This is opposite to the circularly polarized state.     

On optical rotation and selective transmission in ambichiral sculptured thin films

The optical rotation and selective transmission spectra of ambichiral sculptured thin films were calculated using the transfer matrix method. The results of optical modeling showed that at lower angular rotations the optical characteristics of ambichiral sculptured thin films are the same as chiral sculptured thin films. At higher angular rotations, two circular Bragg regimes appear. An ambichiral sculptured thin film in one regime reflects left circularly polarized (LCP) light and in a second regime reflects right circularly polarized (RCP) light. The optical properties of ambichiral sculptured thin films with twist and layer defects as spectral holes are also reported.     

Numerical study of the remittances of axially excited chiral sculptured zirconia thin films

The transmission and reflection spectra from a right-handed chiral sculptured zirconia thin film are calculated using the coupled wave theory and the Bruggeman homogenization formalism in conjunction with the experimental data for the relative dielectric constant of zirconia thin film. The dielectric dispersion function effect on these spectra appeared in wavelengths shorter than the Bragg wavelength. In wavelengths larger than the Bragg wavelength, the dispersion of the dielectric function can be ignored. The results achieved in this work are consistent with the experimental data [Wu, Q.; Hodgkinson, I.J.; Lakhtakia, A. Opt. Eng. 2000, 39, 1863]. A shift towards shorter wavelengths is observed for the Bragg peak with increasing void fraction, which is in agreement with the theoretical work of Lakhtakia [Microw. Opt. Technol. Lett. 2000, 24, 239]. Sorge et al. [Opt. Express 2006, 14, 10550] also found this effect in their experimental results on TiO₂ chiral thin films, while they also found that unlike our results the intensity of the reflectance of the Bragg peak decreases with increasing void fraction. This difference between our theoretical work and Sorge et al.'s experimental work can be related to the structural difference between the idealized theoretical model for chiral films and that obtained in experimental work. In the latter, as Sorge et al. have pointed out the experimental films exhibit a large amount of scattering due to the highly complex and non-ideal structure that the individual chiral elements exhibit.     

Influence of substrate rotation speed on the nanostructure of sculptured Cu thin films

Different rotation speeds of the substrate about its surface normal were used to produce sculptured copper thin films of ∼ 90 nm thickness. X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM) were employed to obtain nano-structure and morphology of these films. Their optical properties were measured by spectrophotometry in the spectral range of 340-850 nm. Real and imaginary refractive indices, film thickness and fraction of metal inclusion in the film structure were obtained from optical fitting of the spectrophotometer data.     

On circular Bragg regimes in ellipsometry spectra of ambichiral sculptured thin films

The generalized ellipsometry formalism was used for a right-handed ambichiral sculptured thin film. The amplitude ratios and phase differences were calculated using an experimental dielectric function for bulk titania. The results showed that the occurrence of the circular Bragg regimes can be adduced from ellipsometry spectra.     

CuInS2薄膜的制备及光学特性

真空共蒸发在玻璃衬底上制备CuInS2薄膜.研究不同Cu、In、S元素配比、不同热处理条件对薄膜的结构、化学计量比及光学性能的影响.实验结果给出:在元素配比中S的原子比x选择极为重要(实验选0.2≤x≤2),本实验Cu、In、S最佳原子比为1:0.1:1.2.用x(Cu).x(In):x(S)=1:0.1:1.2原子比...     

相变光透射特性具有窗口结构的VO2薄膜

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。     

双靶溅射法制备M-SmS光学薄膜的研究

为了制备难以直接获得的金属相SmS,以Sm和Sm2S3为靶材,采用双靶子溅射系统,于单晶Si基板上直接获得了常温常压下稳定存在的M-SmS微晶薄膜,并采用XRD分析、内应力和RBS成分测试等手段对M-SmS的形成机理进行了研究.结果表明:M-SmS薄膜的形成是由于薄膜中存在压应力,压应力的形成与薄膜基板温度、薄膜沉积速率、薄膜中Sm元素过量以及基板之间膨胀系数的差异有关.     

The optical and electrical properties of copper indium di-selenide thin films

Thin films of copper indium di-selenide (CIS) with a wide range of compositions near stoichiometry have been formed on glass substrates in vacuum by the stacked elemental layer (SEL) deposition technique. The compositional and optical properties of the films have been measured by proton-induced X-ray emission (PIXE) and spectrophotometry (photon wavelength range of 300–2500 nm), respectively. Electrical conductivity (σ), charge-carrier concentration (n), and Hall mobility (μ_H) were measured at temperatures ranging from 143 to 400 K. It was found that more indium-rich films have higher energy gaps than less indium-rich ones while more Cu-rich films have lower energy gaps than less Cu-rich films. The sub-bandgap absorption of photons is minimum in the samples having Cu/In ≈ 1 and it again decreases, as Cu/In ratio becomes less than 0.60. Indium-rich films show n-type conductivities while near-stoichiometric and copper-rich films have p-type conductivities. At 300 K σ, n and μ_H of the films vary from 2.15 × 10⁻³ to 1.60 × 10⁻¹ (Ω cm)⁻¹, 2.28 × 10¹⁵ to 5.74 × 10¹⁷ cm⁻³ and 1.74 to 5.88 cm² (V s)⁻¹, respectively, and are dependent on the composition of the films. All the films were found to be non-degenerate. The ionization energies for acceptors and donors vary between 12 and 24, and 3 and 8 meV, respectively, and they are correlated well with the Cu/In ratios. The crystallites of the films were found to be partially depleted in charge carriers.     

离子束后处理对TiO2薄膜光学性质影响的实验研究

采用中频反应磁控溅射方法和线性阳极层离子源实现了TiO2薄膜在线制备和在线离子束后处理。通过对薄膜光学性质的研究,发现氧离子束后处理对提高薄膜折射率,降低薄膜吸收率具有明显效果。为工业生产中,薄膜的在线制备及后处理提供了切实可行的手段。     

化学水浴法制备ZnS薄膜及其光学性能

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.     

Size dependent optical characteristics of chemically deposited nanostructured ZnS thin films

ZnS thin films of different thicknesses were prepared by chemical bath deposition using thiourea and zinc acetate as S²⁻ and Zn²⁺ source. The effect of film thickness on the optical and structural properties was studied. The optical absorption studies in the wavelength range 250–750 nm show that band gap energy of ZnS increases from 3·68–4·10 eV as thickness varied from 332–76 nm. The structural estimation shows variation in grain size from 6·9–17·8 nm with thickness. The thermoemf measurement indicates that films prepared by this method are of n-type.     

热处理对CuInS2薄膜导电类型及光学特性的影响

真空蒸发在载玻片上沉积CuInS2薄膜(Cu、In、S原子配比为1∶0.1∶1.2).摸索CuInS2薄膜发生导电类型转换最有效的热处理条件,研究不同热处理工艺对CuInS2薄膜的结构、表面形貌、化学成分比和光学性能的影响.实验给出:沉积的薄膜进行360℃热处理30 min后,得到黄铜矿结构的CuInS2薄膜;SEN分析显示薄膜表面呈颗粒状较平整致密性略差,导电类型为N型,薄膜的本征吸收限为1.46eV,直接光学带隙Eg=1.38 eV.对薄膜进行370℃热处理20 min同样可得到N型CuInS2但含有少量的CuS2成分,薄膜表面致密性变好但粗糙度增大,本征吸收限发生红移为1.42 eV,Eg=1.40 eV.370℃,30 min热处理后可得到P型CuInS2薄膜,Eg=1.37 eV.制备的三种CuInS2薄膜的光吸收系数都在104 cm-1数量级以上.CuInS2薄膜中In或Cu元素含量大小,对薄膜的导电类型的变化起着决定性的作用,而薄膜中S和In元素的变化直接取决于热处理的条件.     

纳米晶化对CoNbZr薄膜结构及阻抗的影响

采用独特的快速循环纳米晶化技术,对直流磁控溅射制备的非晶CoNbZr软磁膜,进行纳米晶化。研究了在不同的纳米晶化工艺条件下．薄膜的微观结构和阻抗性能。CoNbZr软磁薄膜晶粒细化到30nm．阻抗值从20Ω增加到100Ω(1400MHz),阻抗共振峰向低频移动200MHz左右．极大改善了薄膜的软磁性能。     

HfO2薄膜的制备与光学性能

采用射频磁控反应溅射法，以高纯热压HfO2陶瓷为靶材，在Si衬底上成功制备出HfO2薄膜。系统研究了工艺参数对薄膜沉积速率的影响规律，并对薄膜的光学性能进行了研究。结果表明，射频功率对薄膜沉积速率的影响最为明显，O2／Ar流量比和衬底温度对沉积速率的作用不明显，所制备薄膜的折射率较高在近红外波段趋于1．95，在500-1650nm波段范围内薄膜几乎无吸收，透过率较高。     

氧化锌薄膜的p型掺杂及光学和电学性质研究

为了实现氧化锌薄膜的p型掺杂,从而制备氧化锌同质p-n结,采用化学气相沉积法,以二水合醋酸锌为前驱,醋酸铵为氮源,在氧气氛下制备了氮掺杂的p型氧化锌薄膜.利用X射线光电子能谱和X射线衍射分析,表征了氧化锌薄膜的化学成分.通过霍尔效应测量证实了薄膜的p型导电特性.探讨了制备过程中温度、压强、源物质等条件对反应产物的影响,研究了薄膜的光学和电学特性,得到了p型氧化锌薄膜的吸收光谱和光致发光光谱,以及氧化锌p-n结的伏安特性曲线.     

稀土Ce2O3掺杂TiO2薄膜的结构和光学特性

采用真空热蒸发法在玻璃、单晶硅衬底上制备Ce2O3掺杂TiO2薄膜，研究热处理和Ce2O3掺杂对薄膜性能的影响。结果显示，热处理可明显改善薄膜的结构和光学性能，Ce2O3掺杂可降低薄膜晶型转化温度。TiO2薄膜（玻璃衬底）经600℃热处理由锐钛矿转为金红石结构；当掺Ce2O3含量为5at％时热处理温度为500℃薄膜就已开始发生晶型转变。薄膜表面颗粒较均匀，存在程度不同的孔洞和颗粒聚集现象；掺Ce2O3后薄膜表面致密度明显增强。薄膜（玻璃衬底）的光学带隙从3．74eV降至3．60eV。     

热致变色VO2薄膜的制备及光学性能研究

利用等离子体发射光谱监测系统(PEM)控制钒的等离子强度,在石英基底上磁控溅射制备了VO2薄膜。采用XRD、XPS、SEM、紫外-可见-近红外分光光度计及傅立叶红外分光光度计研究薄膜的结构、光学及相变特性。结果表明,所制备的VO2薄膜具有(011)取向,VO2薄膜的热滞回线宽度为25℃,可见光透过率和太阳光调节率分别可达Tlum,l=34.1%、Tlum,h=35.3%和ΔTsol=6.8%,相变前后,红外光区的反射率变化最大值可达44.4%。     

溶剂体系对c轴择优取向ZnO薄膜结构和光学性质的影响

以无水乙醇、乙二醇甲醚、乙二醇甲醚/乙醇混合溶液(1∶1)为溶剂体系,采用溶胶-凝胶法制备了ZnO透明薄膜,并利用场发射扫描电镜、X射线衍射和反射光谱仪等研究了溶剂体系对薄膜组成、结构和光学性能的影响。结果表明,3种溶剂所制备的ZnO薄膜均为六方纤锌矿型结构,具有c轴择优取向;以乙二醇单甲醚/乙醇混合溶液(1∶1)为溶剂制备的ZnO薄膜平整、致密,在可见光区域透光率达到90%左右,禁带宽度为3.25eV,具备制作薄膜太阳能电池透明导电电极材料的应用价值。     

Effect of annealing on the structural and optical properties of InSe bilayer thin films

InSe bilayer thin films with different thickness were prepared on to a glass substrate by sequential thermal evaporation. Preparation and post deposition treatment conditions were optimized in order to achieve effective bilayer mixing. The influence of bilayer film thickness and annealing temperature on the structural and optical properties was investigated. The prepared films were characterized by X-ray diffraction analysis, scanning electron microscopy, energy dispersive X-ray analysis, UV-Visible spectroscopy, photoconduction and resistivity measurement. Structural studies show that the material undergoes phase transition with thickness, due to co-existence of many phases. Morphological analysis revealed that Se content plays an important role in determining the surface morphology of the film. It has been observed that grain growth and grain splitting phenomena depend on film thickness and annealing temperature. From the photoconduction measurements, the photocurrent increases rapidly when the sample is illuminated using 135 K Lux of white light. Absorption coefficient is in the order of 10⁴ cm⁻¹, makes the InSe thin film useful for the preparation of absorber layer in hybrid solar cell.