Zinc-doped CdS nanoparticles synthesized by microwave-assisted deposition

Cd_1-xZn_xS nanoparticles were grown on pre-cleaned glass substrates using microwave-assisted chemical bath deposition technique. Nanoparticles obtained by this method were smooth, uniform, good adherent, brownish yellow in color where the brightness of the yellow color nature decreases with increasing Zn²⁺ content. The elemental composition analysis confirmed that the nanoparticles comprise of Cd²⁺, Zn²⁺and S^2-. Scanning electron microscope images confirmed the surface uniformity of the Cd_1-xZn_xS nanoparticles devoid of any void, pinhole or cracks and covered the substrate well. The particle size also decreases with increasing Zn ion content. X-ray diffraction (XRD) indicates the hexagonal structure (002) without phase transition. The grain size decreases from 36.45 to 9.60 nm, dislocation density increases from 0.000745 to 0.01085 Line²/m² and lattice parameter decreased from 6.868 to 6.155 nm with increasing Zn²⁺ content. The best transmittance of about 95% was achieved for x=1.0. The nanoparticles showed reduction in the absorbance as Zn ion content increased. Four point probe revealed that the electrical resistivity increased from 1.51×10¹⁰ to 6.67×10¹⁰ Ω ·cm while electrical conductivity decreases from 6.62×10^-11 to 1.49×10^-11 (Ω ·cm)^-1 with increasing Zn²⁺ content. The other electrical properties such as sheet resistance increased from 1.52×10⁸ to 1.58×10⁸Ω, charge carrier mobility decreased from 0.777 to 0.0105 cm²/(V·s) and charge carrier density increased from 1.06×10¹² to 3.95×10¹² cm^-3.     

CdS微晶掺杂TiO2—SiO2复合薄膜的非线性光学特性

采用溶胶－凝胶方法在普通的载玻片上制备了ＣｄＳ微晶掺杂的ＴｉＯ２－ＳｉＯ２复合薄膜。用正硅酸乙酯、钛酸丁酯、醋酸镉作原料，比较了硫脲和硫化乙氨的硫化作用。不同热处理温度、时间的吸收光谱表明，薄膜中存在着量子尺寸效应。采用Ｚ－Ｓｃａｎ技术测量了薄膜的非线性吸收及非线性折射率。     

Photoluminescence of erbium-doped aluminum oxide films with embedded silicon nanoparticles

Erbium-doped aluminum oxide films with embedded Si nanoparticles have been obtained by magnetron puttering of a composite (Al + Er₂O₃ + Si) target and subsequent electrochemical anodization at room temperature. The photoluminescence (PL) spectra of these films are measured in the temperature range 4.2–300 K. Efficient PL is observed at a wavelength of 1.54 μm without preliminary annealing of the samples, which indicates the possibility of activating Er³⁺ ions without any high-temperature treatment. The aluminum oxide films with embedded Si nanoparticles were observed to show stronger PL at a wavelength of 1.54 μm than similar films without Si nanoparticles. This effect can be explained by additional pumping of Er-based luminescence centers and energy transfer from the Si nanoparticles.     

Optical absorptive response of platinum doped TiO2 transparent thin films with Au nanoparticles

In this paper different optical absorption bands associated to the surface plasmon of resonance of a nanoparticle containing sample were achieved by a sol–gel processing route. We study the linear and nonlinear optical absorptive properties of a titanium dioxide thin film with superficial Au nanoparticles. A chaotic behavior related with modification of the optical absorption by a multi-wave mixing interaction was investigated. A characteristic Mandelbrot group tendency was used to describe the possibility of a resulting absorptive response. The analysis of the observations showed that an excitation at 488 nm wavelength in the nanocomposite can originate a measurable change in the absorptive properties for the propagation of optical beams at 532 nm and at 650 nm. However, the inhibition of this condition exhibited by the film can be obtained by the shift of its plasmonic response. It is considered that the near resonance participation of the Au nanoparticles is mainly responsible for avoiding the photodarkening contribution to the optical absorptive response of the sol–gel TiO₂ film with embedded Au nanoparticles. Potential applications of the samples are proposed for development of optical sensors or transparent thin films for filtering functions.     

Electrophoretic deposition of CdS colloidal nanoparticles onto an amorphous silicon membrane

A method for producing nanoporous silicon membranes suspended over the microchannels of a silicon matrix is proposed. Solid concentrates of CdS nanoparticles are produced by electrophoretic deposition onto this thin-film carrier. The results of complex studies that confirm the formation of a Si-CdS composite in the regions of ion-current flow through the porous membrane are reported. It is shown that the gradual accumulation of semiconductor nanoparticles encapsulated in thioglycolic-acid organic shells occurs during electrophoresis. It is inferred that a similar technological approach is applicable also to biological substances, whose dosed concentrates can be used in biomedical investigations.     

Pulsed laser deposition of PMN thin films

Lead magnesium niobate (Pb(Mg_1/3Nb_2/3)O₃ or PMN) thin films have been deposited on different substrates by pulsed laser deposition. Film composition was studied by secondary ion mass spectroscopy and their crystallinity by X-ray diffraction techniques. Small-signal dielectric constant and loss factor of the films have been measured as a function of temperature and frequency on structures with 3 mm diameter evaporated Au top electrodes, by using an impedance analyser. The obtained PMN films have been found polycrystalline and partially oriented, with a certain amount of secondary pyrochlore phases and interface phases which are detrimental for the overall dielectric constant and modifies the behaviour of the heterostructures. Polarization hysteresis measurements performed at different temperatures below and above the dielectric maximum temperature T_m showed the persistence of polarization above T_m.     

脉冲激光纳米薄膜制备技术

脉冲激光薄膜沉积（ＰＬＤ）是近年来受到普遍关注的制膜新技术。简要介绍了该技术的物理原理;探讨了脉冲激光沉积制膜的物理过程,激光作用的极端条件及等离子体羽辉形成的控制对薄膜成长的影响;评价了脉冲激光沉积技术在多种功能材料薄膜,特别是纳米薄膜及多层结构薄膜的制备方面的特点和优势,结合自行研制的设备,介绍了在ＰＬＤ基础上发展起来的兼具分子束外延（ＭＢＥ）技术特点的激光分子束外延技术（Ｌ－ＭＢＥ）,指出脉冲激光沉积技术在探讨激光与物理相互作用和薄膜成膜机理方面的作用,尤其是激光分子束外延技术在高质量的纳米薄膜和超晶格等人工设计薄膜的制备上显现出的巨大潜力。     

沉积温度对多元醇法制备硫化镉薄膜的影响

CdS thin films were successfully deposited onto glass substrates for the first time by the polyol method using cadmium acetate, thiourea and diethylene glycol as the raw materials. The effects of the deposition tempera- ture from 120 to 200 ℃ in steps of 20 ℃on the structure, morphology and optical properties of the resultant films were investigated. It was found that the crystallinity was improved and the value of the surface average roughness was decreased with increasing the deposition temperature. The average grain sizes of the CdS thin films were 77.16 and 76.61 nm at 140 and 180 ℃, respectively. All samples showed excellent transmittance and the band gaps were found to reduce from 2.55 to 2.45 eV with the increase of the deposition temperature, which was attributed to the improvement of crystallinity.     

脉冲激光扫描淀积类金刚石薄膜

采用能量密度为1.178×109W/cm2的XeCl准分子激光直接辐照高纯度的石墨靶,并同时采用辅助放电,在1×10-5Torr的真空环境中,于温度为80℃的Si(100)的基片上淀积出类金刚石薄膜,Raman光谱显示在1330cm-1处出现较强的散射峰值;对薄膜红外光谱进行测试,其光谱在2900cm-1处有吸收峰,表明所淀积的类金刚石薄膜含有C-H键,其H元素与C元素的比为45%.薄膜的电阻率为1.89×106Ω/cm,通过光吸收测得的该薄膜的能隙为1.55eV.     

Design principles for light trapping in thin silicon films with embedded dielectric nanoparticles

We investigate the light‐trapping effects of dielectric nanoparticles embedded within the active semiconductor layer of a thin‐film solar cell. The baseline model consists of a 1·0 µm slab of crystalline silicon on an aluminum back contact topped with a 75 nm Si₃N₄ anti‐reflective coating. Using finite‐difference time‐domain simulations, we calculate the absorption gain due to a periodic array of SiO₂ nanospheres with characteristic depth, diameter, and pitch. Under optimal conditions, absorption gain due to embedded spheres can reach as high as 23·4% relative to the baseline geometry. Using Au‐core/SiO₂‐shell nanoparticles, it is even possible to reach 30%. We then infer a series of design principles from our data that include trade‐offs between broadband scattering efficiency, poor absorption at long wavelengths, and semiconductor displacement. We also find that the optimal spacing between particles is approximately 400 nm. Above this distance, each scatterer acts in near isolation from any neighboring particles, and absorption gain is approximately linear with area coverage. Such gains are also expected for disordered as well as ordered arrays. These results demonstrate the potential of embedded dielectric nanoparticles as a tool for enhancing carrier generation in thin silicon solar cells. Copyright © 2011 John Wiley & Sons, Ltd.     

Comparative study between CBD and SILAR methods for deposited TiO2, CdS,and TiO2/CdS core-shell structure

TiO₂, CdS, and TiO₂/CdS core–shell structures were deposited on fluorine-doped tin oxide (FTO)-coated glass substrate using chemical methods. TiO₂ thin films were prepared by chemical bath deposition (CBD) and successive ionic layer adsorption and reaction (SILAR). SILAR was also utilized to deposit CdS film on TiO₂ thin film. The structural, surface morphology, and optical characteristics of FTO/TiO₂, FTO/CdS, and FTO/TiO₂/CdS core- shell structures were evaluated. The FTO/TiO₂ films produced by both methods conformed to anatase and rutile phase structures. Corresponding XRD pattern of the FTO/TiO₂/CdS sample exhibited one peak corresponding to hexagonal (101) for CdS. Scanning electron micrographs showed nanorod structures for the TiO₂ thin films deposited by CBD, contrary to the nanograin structure formed by SILAR. Optical results showed highly extended absorption edge to the visible region for the FTO/TiO₂/CdS structure deposited by the two methods. The TiO₂ thin films deposited by CBD exhibited higher absorption in the visible region than nanograined TiO₂ thin films deposited by SILAR because of the high surface area of the TiO₂ nanorod. Photoelectrochemical (PEC) properties of FTO/TiO₂, and FTO/TiO₂/CdS system were also examined. PEC behavior of FTO/TiO₂/CdS was compared with that of FTO/TiO₂ deposited by CBD and SILAR. The TiO₂ nanorod thin films deposited by CBD showed evidently enhanced PEC performance compared with nanograined TiO₂ thin films deposited by SILAR.     

用脉冲激光沉积法制备类金刚石膜及金刚石薄膜

简要评述了用脉冲激光沉积技术制备类金刚石膜及金刚石薄膜的研究进展，总结了激光脉冲沉积制备薄膜的基本原理及其特点，分析了激光波长，能量，衬底温度等对薄膜质量的影响。     

氧离子束辅助沉积氧化铪薄膜光学属性的研究

电子枪蒸发制备了氧化铪薄膜,对氧离子束辅助和未辅助两种情况下的样品进行了折射率、吸收、激光损伤阈值等属性的测试,结果表明,氧离子束辅助沉积的样品与未辅助沉积的样品相比具有高的折射率和高的吸收,以及稍低的激光损伤阈值。经过分析发现,薄膜的激光损伤阈值是影响薄膜抗激光特性的不利因素和有利因素竞争的结果,离子束辅助沉积技术在引入结构致密等有利因素的同时,也引入了吸收增加等不利因素。     

高功率CO2激光薄膜的离子辅助镀工艺进展

真空蒸发镀膜技术已经应用了很多年，随着激光技术的发展，人们对激光薄膜尤其是高功率激光薄膜的质量要求越来越高，离子辅助沉积薄膜技术已被广泛用来作为一种改善光学薄膜特性的工艺手段。本文简单地介绍了这项技术的原理及国内外研究现状；总结了该技术的优、缺点；客观评价了该技术的应用前景；对该技术今后的研究方向提出了建议。     

脉冲激光溅射沉积YBCO超导薄膜

从激光与材料相互作用理论出发,分析了激光烧蚀材料等离子体羽辉的空间运动特征和成分分布;以YBCO/SrTiO_3为对象,从实验上系统研究了脉冲激光溅射沉积薄膜过程中薄膜质量与基片温度、基片-靶材距离、气体压强、激光脉冲能量以及重复频率等参数的关系;总结出在SrTiO_3(100)单晶基片上溅射沉积YBCO高温超导薄膜的最佳实验参数。     

Characterization and antibacterial capabilities of nanocrystalline CdS thin films prepared by chemical bath deposition

Antibacterial capabilities of nanocrystalline cadmium sulfide (CdS) thin films have been developed against Gram-positive and Gram-negative bacteria in dark and sunlight at 60 °C. For this purpose, a strain of Gram-positive Staphylococcus aureus, and two strains of Gram-negative bacteria (Pseudomonas aeruginosa, and Escherichia coli) were used. The nanocrystalline CdS thin films have been prepared using a chemical bath deposition (CBD) method at different thicknesses (50, 80 and 100 nm). The different deposition parameters including the speed of rotation of substrate, temperature of chemical bath, pH of solution and time of the deposition were optimized. The Polyvinylpyrrollidone (PVP) was successfully used as capping agent in order to stop the agglomeration in the CdS thin films. It was found that, CdS thin films have remarkable antibacterial activity in dark and sunlight and it could be applied as antimicrobial agent in medical field. In order to confirm the crystalline structure of CdS thin films, the polycrystalline nature of the deposited CdS thin films with hexagonal structure was obtained. Furthermore, the structural parameters including lattice parameters, cell volume, the space group, average grain size, dislocation density and the strain have been calculated. The topography and surface roughness of the CdS thin films have been studied before and after the bacteriostatic effect using Scanning Electron Microscopy (SEM). Furthermore, the compositions of nanocrystalline CdS thin films have been evaluated using Energy Dispersive X-ray emission (EDX) and a Transmission Electron Microscope (TEM). Based on the optical measurements in the range of 300–2500 nm, the band gap energy of the prepared CdS thin films was found to be 2.4 eV.     

GaN薄膜制备及脉冲激光沉积法的研究进展

介绍了国内外制备GaN材料的历史和现状。分析了GaN材料及其薄膜的各种制备工艺的特点,并详细介绍了采用激光沉积工艺制备GaN薄膜的研究进展。     

用脉冲激光沉积法在Al2O3上沉积类金刚石薄膜

为了研究沉积时间和衬底温度对类金刚石薄膜的影响,在用脉冲激光沉积法在Al2O3衬底上制备类金刚石薄膜的实验中,保持其他实验参数不变,先取沉积时间分别为15 min和40 min来沉积薄膜;再取衬底温度分别30℃和300℃来沉积薄膜.用显微镜观察薄膜是否有起皱现象,用Raman光谱仪检测薄膜的微观结构,用原子力显微镜检测...     

Pulsed laser deposition of ITO thin films and their characteristics

The indium tin oxide (ITO) thin films are grown on quartz glass substrates by the pulsed laser deposition method. The structural, electrical, and optical properties of ITO films are studied as a function of the substrate temperature, the oxygen pressure in the vacuum chamber, and the Sn concentration in the target. The transmittance of grown ITO films in the visible spectral region exceeds 85%. The minimum value of resistivity 1.79 × 10⁻⁴ Ω cm has been achieved in the ITO films with content of Sn 5 at %.     

Enhanced photocatalytic performance of platinized CdS/TiO2 by optimizing calcination temperature of TiO2 nanotubes

TiO₂ nanotubes were prepared by hydrothermal treatment of TiO₂ powder in NaOH aqueous solution and then calcined at various temperatures. The post-calcination treated TiO₂ nanotubes were decorated with CdS by wetness impregnation and subsequently sulfurization to fabricate CdS/TiO₂ composites. The photocatalytic performance of CdS/TiO₂ composites toward hydrogen production from water splitting was investigated. The results show that the calcination temperature of TiO₂ nanotubes has a significant effect on the photocatalytic performance of CdS/TiO₂. With the increase of calcination temperature from 300 to 500 °C, the crystallinity of TiO₂ nanotubes is increased resulting in the enhanced photocatalytic performance of CdS/TiO₂. When the calcination temperature is higher than 500 °C, TiO₂ nanotubes gradually transform into nanorods and finally completely collapse, which leads to the decrease of photocatalytic performance of CdS/TiO₂. The CdS/TiO₂ composite with TiO₂ nanotubes calcined at 500 °C exhibits the highest hydrogen evolution rate, which could be attributed to its 1 D nanotubular structure and good crystallinity.