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利用在线椭偏仪对非晶碳氢膜进行了光学常数、沉积率和刻蚀率的测量。在无直流负偏压或偏压较小时,薄膜呈现聚合物结构,折射率和消光系数较小;当增加直流负偏压时,薄膜的折射率和消光系数显著提高,所成膜为硬质非晶碳氢膜。在以CH4作为气源进行沉积时,随着偏压的增加,沉积率先升高再降低,在偏压为-100V时,沉积率为最大。H2/N2(30%N2)的混合气体的刻蚀率要比单独用H2作为刻蚀气体的刻蚀率要大。对于CH4/N2(30%N2),在偏压从0V增加到300V过程中,在大约50V时,基底上的薄膜有一个从沉积到刻蚀的转化过程。     

近红外波段锑基铋掺杂薄膜厚度对光学常数与光学带隙的影响

采用磁控溅射法制备了不同厚度的锑基铋掺杂薄膜,用X射线衍射(XRD)和透射电子显微镜(TEM)研究了薄膜结构随厚度的变化。利用椭圆偏振法测定了样品薄膜在近红外波段的光学常数与光学带隙,研究了膜厚对样品薄膜光学常数和光学带隙的影响。结果表明,膜厚从7 nm增加至100 nm时,其结构由非晶态转变为晶态。在950～2200 nm波段,不同厚度薄膜样品的折射率在4.6～8.9范围,消光系数在0.6～5.8范围,光学带隙在0.32～0.16 eV范围。随着膜厚的增加,薄膜的折射率和光学带隙减小,而消光系数升高;光学常数在膜厚50 nm时存在临界值,其原因是临界值前后薄膜微观结构变化不同。     

非晶金刚石薄膜的X射线反射研究

利用过滤阴极真空电弧系统制备了不同衬底偏压下非晶金刚石薄膜,分别采用X射线反射法测定了相应的非晶金刚石膜密度,分析了薄膜密度与沉积能量之间的变化规律．建立了薄膜密度随衬底偏压的变化曲线。研究发现在-80V时非晶金刚石膜密度存在最大值3．26g／cm^2,随着偏压的增大和减小,薄膜的密度都相应的下降;当衬底偏压加到-2000V时,密度减小到2．63g／cm^2,相对于密度的最大值变化较小。通过薄膜sp^3能态杂化含量与密度的简单比例关系,近似推算出非晶金刚石膜中sp^3能态的含量最高可达80％以上。     

溅射气压对Ge2Sb2Te5薄膜光学常数的影响

实验研究了氩气气压对溅射制备的Ge2 Sb2 Te5 薄膜的光学常数随波长变化的影响 ,结果表明 :随薄膜制备时氩气气压的增加 ,Ge2 Sb2 Te5 薄膜的折射率n先增大后减小 ,而消光系数k先减小后增大。二者都随波长的变化而变化 ,且在长波长范围变化较大 ,短波长范围变化较小 ,解释了溅射气压对Ge2 Sb2 Te5 薄膜的光学常数影响的机理     

射频功率对类金刚石薄膜性能的影响

在不同射频功率条件下,实验研究了射频等离子体化学气相沉积类金刚石薄膜的金刚石相分数、光学常数和硬度。利用Raman光谱仪、椭圆偏振仪、数字式显微硬度计分别测试了不同条件下单层类金刚石薄膜的金刚石相分数、光学常数和硬度。实验表明,随着功率的增加,金刚石相的相对分数减少,薄膜的折射率先减小再增加然后减小,射频功率大于910 W时,沉积速率急剧增大。而薄膜的硬度先增加后减小,在射频功率为860 W处获得最大值。     

热舟蒸发LaF3薄膜的紫外性能研究

研究了沉积温度对热舟蒸发氟化镧薄膜结构和光学性能的影响,沉积温度从200℃上升到350℃.间隔为50℃.采用分光光度计测量了样品的透射率和反射率光谱曲线,并在此基础上进行了光学损耗、光学常数以及带隙和截止波长的计算.采用表面轮廓仪进行了表面形貌和表面粗糙度的标定,采用X射线衍射(XRD)方法测量了不同沉积温度下样品的微结构.发现在短波长波段,随着沉积温度的升高,光学损耗增加,晶粒尺寸增大,表面粗糙度略有增加.不过散射损耗在光学损耗中所占比例均很小,光学损耗的增加主要由吸收损耗引起.随着沉积温度的升高,折射率与消光系数增大,带隙变小,相对应的截止波长向长波方向移动.     

椭偏法表征四面体非晶碳薄膜的化学键结构

采用自主研制的双弯曲磁过滤阴极真空电弧(FCVA)技术,在不同衬底负偏压下制备了四面体非晶碳(ta-C)薄膜。通过分光光度计和椭偏(SE)联用技术精确测量了薄膜厚度,重点采用椭偏法对不同偏压下制备的ta-C薄膜sp3 C键和sp2 C键结构进行了拟合表征,并与X射线光电子能谱(XPS)和拉曼光谱的实验结果相对比,分析了非晶碳结构的椭偏拟合新方法可靠性。结果表明,在-100V偏压时薄膜厚度最小,为33.9nm;随着偏压的增加,薄膜中的sp2 C含量增加,sp3 C含量减小,光学带隙下降。对比结果发现,椭偏法作为一种无损、简易、快速的表征方法,可用于ta-C薄膜中sp2 C键和sp3 C键含量的准确测定,且在采用玻璃碳代表纯sp2 C的光学常数及拟合波长选取250～1700nm时的椭偏拟合条件下,拟合数值最佳。     

基于透射光谱确定溶胶凝胶ZrO2薄膜的光学常数

基于溶胶凝胶ZrO₂薄膜的紫外/可见/近红外透射实验光谱,采用Swanepoel方法结合Wemple-DiDomenico色散模型,方便地导出了ZrO₂薄膜在200—1200nm波长范围内的光学常数,包括折射率、色散常数、膜层厚度、吸收系数及能量带隙.研究发现,溶胶凝胶ZrO₂薄膜具有高折射率(1.63—1.93,测试波长为632.8nm)、低吸收和直接能量带隙(4.97—5.63eV) 等光学特性,而且其光学常数对薄膜制备过程中的重要工艺 关键词： 光学常数 Swanepoel方法 2薄膜')" href="#">ZrO₂薄膜 热处理     

退火对磁控溅射HfSi_xO_y薄膜光学性质的影响

采用射频反应磁控溅射方法在硅衬底制备了HfSixOy薄膜,用X射线光电子能谱(XPS)分析了HfSixOy薄膜的成分,用X射线衍射(XRD)检测了薄膜的结构,并用椭圆偏振光谱仪研究了退火处理对薄膜光学性质的影响。XRD谱显示,HfSixOy薄膜经700℃高温退火处理后仍为非晶态,而在900℃高温退火处理后出现晶化。采用Tauc-Lorentz(TL)色散模型对测试得到的曲线进行拟合并分析得出薄膜的光学常数,结果表明,薄膜的折射率随退火温度的升高而增加,而消光系数随退火温度的升高呈降低趋势。薄膜的光学带隙随着退火温度的升高增加,采用外推法得到薄膜沉积态和经500℃,700℃,900℃退火后的带隙分别为5.62,5.65,5.68,5.98eV。     

不同沉积温度下非晶硅光学薄膜的光学特性研究

光学薄膜的光学特性是薄膜设计与制备的基础。硅材料是红外光学薄膜中一种重要的高折射率材料。研究了在不同沉积温度下非晶硅光学薄膜的折射率和消光系数的变化。结果表明,在200℃时,硅薄膜折射率最大,消光系数随温度升高而减小。     

采用椭偏法结合分光光度法研究极薄银的光学常数

极薄银在滤光片、高反射镜等中有广泛的应用,其光学常数严重影响着膜系的特性。在室温条件下,采用电阻热蒸发技术分别在硅和玻璃基底上沉积5.3 nm~26 nm不同厚度的极薄银薄膜,用TalySurfCCI非接触式轮廓仪测量了薄膜的厚度,研究了不同厚度银薄膜的光学常数n和k。镀制厚度5.3 nm、7.9 nm、14.1 nm、26.0 nm的银薄膜,结果显示极薄银的光学常数与块状银光学常数不同,当膜厚小于14.1 nm时,折射率n在380 nm~600 nm随波长增加而增加,在600 nm~1 600 nm随波长增加缓慢减小至趋于稳定值2.6;消光系数k在380 nm~500 nm随着波长增加而增加,在500 nm~1 600 nm随波长增加而缓慢减小至趋于0不变;当膜厚大于14.1 nm时,折射率随波长增加而增加,消光系数随波长近似呈线性增加。整体上,膜厚增加时折射率减小且趋于块状银的折射率,k随厚度增加而增加并最终趋于块状膜。用此拟合的光学常数代入TFc膜系设计软件计算其透射率,发现与分光光度计测得的透射率吻合较好。     

多孔阳极氧化铝薄膜光学常数的确定

根据多孔阳极氧化铝(AAO)薄膜的实验透射谱(200—2500nm)，采用极值包络线算法确定其光学常数，并由此较精确地计算出AAO薄膜样品在该波段的光学常数.结果表明，多孔氧化铝薄膜表现出直接带隙(能隙约4．5eV)半导体的光学特性，且其光学常数与制样中的重要工艺参数阳极氧化电压有显著的相关性，即随阳极氧化电压的增加，AAO薄膜的厚度、折射率和光学能隙变大，消光系数减小．同时，计算得到的薄膜厚度与实测值相吻合，则说明计算结果和实验值是自洽的. 关键词： 薄膜光学 光学常数 多孔阳极氧化铝 阳极氧化电压     

Synthesis and optical characterization of nanocrystalline CdTe thin films

From several years the study of binary compounds has been intensified in order to find new materials for solar photocells. The development of thin film solar cells is an active area of research at this time. Much attention has been paid to the development of low cost, high efficiency thin film solar cells. CdTe is one of the suitable candidates for the production of thin film solar cells due to its ideal band gap, high absorption coefficient. The present work deals with thickness dependent study of CdTe thin films. Nanocrystalline CdTe bulk powder was synthesized by wet chemical route at pH≈11.2 using cadmium chloride and potassium telluride as starting materials. The product sample was characterized by transmission electron microscope, X-ray diffraction and scanning electron microscope. The structural characteristics studied by X-ray diffraction showed that the films are polycrystalline in nature. CdTe thin films with thickness 40, 60, 80 and 100 nm were prepared on glass substrates by using thermal evaporation onto glass substrate under a vacuum of 10⁻⁶ Torr. The optical constants (absorption coefficient, optical band gap, refractive index, extinction coefficient, real and imaginary part of dielectric constant) of CdTe thin films was studied as a function of photon energy in the wavelength region 400–2000 nm. Analysis of the optical absorption data shows that the rule of direct transitions predominates. It has been found that the absorption coefficient, refractive index (n) and extinction coefficient (k) decreases while the values of optical band gap increase with an increase in thickness from 40 to 100 nm, which can be explained qualitatively by a thickness dependence of the grain size through decrease in grain boundary barrier height with grain size.     

Effect of indium incorporation on the optical properties of spray pyrolyzed Cd0.22Zn0.78S thin films

In this study, effect of indium incorporation on the optical properties is investigated for the spray pyrolyzed onto glass substrates at 275°C substrate temperature undoped and indium doped Cd_0.22Zn_0.78S thin films. The average optical transmittance of all the films was over 77% in the wavelength range between 450 and 800 nm. The optical band gap energies of the thin films have been investigated by the measurement of the optical absorbance as a function of wavelength. The optical absorption studies reveal that the transitions are direct band gaps of 3.02 and 3.05 eV for undoped and doped indium Cd_0.22Zn_0.78S thin films, respectively. The Urbach tail parameter and optical constants such as refractive index, extinction coefficient, and dielectric constants were calculated for these films. The dispersion parameters such as single-oscillator energy and dispersive energy were discussed in terms oft he single-oscillator Wemple—DiDomenico model.     

Determination of optical properties in nanostructured thin films using the Swanepoel method

We present the methodological framework of the Swanepoel method for the spectrophotometric determination of optical properties in thin films using transmittance data. As an illustrative case study, we determined the refractive index, thickness, absorption index, and extinction coefficient of a nanostructured 3 mol% Y₂O₃-doped ZrO₂ (yttria stabilized zirconia, 3YSZ) thin film prepared by the sol-gel method and deposited by dipping onto a soda-lime glass substrate. In addition, using the absorption index obtained with the Swanepoel method, we calculated the optical band gap of the film. The refractive index was found to increase, then decrease, and finally stabilize with increasing wavelength of the radiation, while the absorption index and extinction coefficient decreased monotonically to zero. These trends are explained in terms of the location of the absorption bands. We also deduced that this 3YSZ thin film has a direct optical band gap of 4.6 eV. All these results compared well with those given in the literature for similar thin films. This suggests that the Swanepoel method has an important role to play in the optical characterization of ceramic thin films.     

沉积工艺条件对金刚石薄膜红外椭偏光学性质的影响

采用红外椭圆偏振光谱仪对不同工艺条件下制备的CVD金刚石薄膜在红外波长范围内的光学参量进行了测量，分析了工艺条件对金刚石薄膜红外光学性质的影响.获得了最佳的沉积工艺参数，优化了薄膜的制备工艺.结果表明薄膜的折射率和消光系数与薄膜质量密切相关，当温度为750℃，碳源浓度为0.9%和压强为4.0 kPa时，金刚石薄膜的红外椭偏光学性质最佳，折射率平均值为2.385，消光系数在10^-4范围内，在红外波段具有良好的透过性. 关键词： 薄膜光学 红外光学性质 工艺条件 金刚石薄膜     

Optical properties of SrTiO<Subscript>3</Subscript> thin films by pulsed laser deposition

SrTiO₃ thin films were prepared on a fused-quartz substrate by pulsed laser deposition (PLD). Dense and homogeneous films with a thickness of 260 nm were prepared. Optical constants (refractive index n and extinction coefficient k) were determined from the transmittance spectra using the envelope method. The optical band gap energy of the films was found to be 3.58 eV, higher than the 3.22 eV for bulk SrTiO₃, attributable to the film stress exerted by the substrate. The dispersion relation of the refractive index vs. wavelength follows the single electronic oscillator model. The refractive index and the packing density for the PLD-prepared SrTiO₃ thin films are higher than those for the SrTiO₃ films prepared by physical vapor deposition, sol–gel and RF sputtering. Received: 18 March 2002 / Accepted: 7 October 2002 / Published online: 8 January 2003 RID="*" ID="*"Corresponding author. Fax: +86-25/359-5535, E-mail: mszhang@nju.edu.cn     

Optical properties of MnAl films

The optical properties of MnAl films of different compositions, deposited at different substrate temperatures and in the thickness range 25 to 90 nm, are reported. The reflectance and transmittance are measured in the wavelength range 320–900 nm for near normal incidence of light. These measurements are used to calculate the optical constants namely, refractive index (n) and extinction coefficient (k). The wavelength and thickness dependence of these optical constants are reported. The optical measurements for films with higher Mn content and grown at higher substrate temperature reveal that n and k values are constant over a wide wavelength range (500–900 nm) showing high reflectance in the visible and near infrared region.     

Effect of annealing temperature on the optical constants of zinc oxide films

In this paper, the effect of annealing temperature on optical constants was studied. The ZnO films were deposited on microscopic glass substrates using the sol-gel method for various annealing temperatures. The deposited zinc oxide (ZnO) films were characterized by an X-ray diffractometer (XRD), a spectrophotometer and scanning electron microscopy (SEM). The transmittance spectra recorded through the spectrophotometer exhibits 90% transmittance. The XRD spectra showed polycrystalline nature of ZnO film. Optical constants were determined through transmittance spectra using an envelope method. It was found that there was a significant effect of annealing temperature on the refractive index and extinction coefficient of deposited ZnO films. In this experiment, the optimum refractive index value of 1.97 was obtained at 350 °C annealing temperature at visible (vis) wavelength. The optical energy gap was found to be of ∼3.2 eV for all the samples. The top view of SEM showed the ZnO grain growth on the glass substrates.