Studies on chemical bath deposited SnS2 films for Cd-free thin film solar cells

Tin disulfide (SnS₂) is a simple binary metal chalcogenide and it has been proposed as a promising buffer material for Cd-free thin film solar cells. The present work explores the deposition of SnS₂ films by a facile chemical bath deposition at different deposition times in the range of 30–120 min. The effect of deposition time on the structural, optical and electrical properties was investigated. The as-grown SnS₂ films showed a hexagonal crystal structure with a high intensity (001) peak at 15.03°. The films showed shuttle shaped grains that were uniformly distributed across the surface of the substrate. The films showed an optical energy band gap in the range of 2.95–2.80 eV. PL spectra showed a strong emission peak in the wavelength range, 410–460 nm with the variation of deposition time. The SnS₂ films prepared at a deposition time of 90 min showed good crystallinity and morphology with low resistivity of 11.2 Ω-cm. A solar cell with device structure of Mo/SnS/SnS₂/i-ZnO/Al: ZnO/Ni/Ag was fabricated. The fabricated solar cell showed an efficiency of 0.91%, which validate the photovoltaic performance of SnS₂ films.     

Microstructure and electrochemical properties of electron-beam deposited Sn-Cu thin film anodes for thin film lithium ion batteries

Thin film Sn-Cu anodes with high Cu content were prepared by electron-beam evaporation deposition using Cu substrate as current collector. Annealing, with the condition being determined by DSC, was used to improve the performance of these electrodes. X-ray diffraction (XRD), scanning probe microscopy (SPM), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) were used to characterize the structure and composition of the Sn-Cu thin film electrodes. Cyclic voltammetry and galvanostatical charge-discharge measurement were carried out to characterize the electrochemical properties of the as-deposited and annealed electrodes. ?-Cu₃Sn intermetallic phase was formed and interface strength between deposited active materials layer and current collector was enhanced by annealing the as-deposited film under suitable condition. The annealed thin film electrode showed good cycleability and had no phase change during cycling. Although large initial capacity loss was found associated with SEI formation due to increase of surface roughness of annealed electrode, a stable discharge capacity near 300 mAh/g with Coulomb efficiency of about 96% was obtained at voltage window of 0.1-2.0 V and a discharge capacity of about 200 mAh/g and Coulomb efficiency of 97% were kept stable up to 30th cycle at a narrower voltage window of 0.2-1.5 V versus Li/Li⁺.     

Optical properties of the thin films of poly(methylpentoxysilane) homopolymers and copolymers

The optical properties of the thin films of asymmetrically substituted polysilane homopolymers and copolymers were studied. A conformational change in the organopolysilanes having (pentoxy,methyl) or (hexyl,methyl) groups was observed by polarized UV spectrometry and a wide angle X-ray diffraction. The polysilanes and polysilane copolymers having hexyl and pentoxy side chains were crystallized to form oriented films along the direction of the mechanically oriented polytetrafluoroethylene (PTFE) films. The bathochromic shifts were observed for polysilane and the polysilane copolymer having pentoxy side chains when the film thickness was small (ca. <50 nm). The influence of the thickness of the films on the spectral change was significant when the substituent was a pentoxy group, however, not when it was a hexyl group.     

Influence of process conditions on structural and electrochemical properties of lithium phosphorus oxynitride thin films

Lithium phosphorus oxynitride (LiPON) is the most representative solid electrolyte in thin film battery applications. In addition, it has been used as an interfacial protective layer to improve the stability of cathode and anode materials. In this article, we review the effect of the process conditions on the structural and electrochemical properties of LiPON thin films. A common method to form LiPON thin films is radiofrequency (RF) sputtering; much research has been conducted to optimize the corresponding process parameters, such as RF power density, working pressure in nitrogen atmosphere, substrate temperature, substrate bias power, post-annealing, and sputtering target. Many studies have characterized LiPON films obtained with various process parameters, but significant differences have been observed in the reported trends. The most representative difference involves the N_t/N_d ratio, which has been reported to be either directly or inversely proportional to the ionic conductivity. Recently, controversial results have been obtained on the N-based local structure of LiPON thin films. The structural argument relies on the idea that nitridation promotes cross-linking via the formation of doubly and triply coordinated N bridges between P atoms. In addition to further research to clarify these issues, it is necessary to introduce new methods for the interpretation of data based on it.     

High-temperature electrical properties of polymer-derived ceramic SiBCN thin films fabricated by direct writing

The in situ temperature monitoring of hot components in harsh environments remains a challenging task. In this study, SiBCN thin-film resistance grids with thicknesses of 1.8 μm were fabricated on alumina substrates via direct writing. Owing to their dense microscopic morphology and extremely high graphitisation level, the produced SiBCN films exhibited large high-temperature oxidation resistance and electrical conductivity. The resistance–temperature, stability, and repeatability characteristics of these films were examined in an aerobic environment at temperatures up to 800 °C. The obtained results revealed that the thermistor resistance decreased monotonously with increasing temperature from room temperature to 800 °C. The SiBCN film resistance variations observed during repeated temperature cycling in the regions of 505–620 °C and 610–720 °C were 0.09% and 1.7%, respectively. The high cyclability and stability of the SiBCN thin film thermistor suggested its potential applicability for the in situ temperature monitoring of hot components in harsh environments.     

微波水热法制备硫化锡纳米晶及其光学性质的研究

以氯化亚锡和硫化铵为前驱物采用微波水热法合成硫化锡纳米晶,采用XRD和TEM对合成物的晶型和形貌进行表征。结果表明:制备的样品为斜方晶体结构的多晶硫化锡粉体,晶粒形状为近球形。随着反应温度的升高,硫化锡纳米晶的晶粒尺寸从20 nm增至50 nm;随着反应时间的延长,硫化锡纳米晶的晶粒尺寸呈增大趋势。利用紫外可见光谱分析,硫化锡纳米晶的光学带隙约为1.61 eV。     

Ordering of block copolymer/nanoparticle composite thin films

The ordering behavior of polymer nanocomposites composed of gold nanoparticles confined in the polystyrene (PS) domains of PS based block copolymers was investigated. The results reveal that the self‐assembly of nanoparticles in the PS domains improved the ordering of microdomains. This is attributed to the presence of nanoparticles that reduced the degree of segregation of the system, causing slow phase separation. This facilitates the packing of the cylindrical microdomains, leading to a well‐ordered structure of the composite. When particles were incorporated into the major domains of cylindrically ordered block copolymer, the connectivity of the domains allowed particles to move to the top of the film to gain additional entropy of the system. In contrast, when particles were organized in parallel cylinders in the block copolymer, they were confined in the cylinders which prevented them from diffusing in the depth direction. The aggregation of nanoparticles was amplified when the composite was annealed in air. We believe that the results from this study will enable more understanding of the effects of nanoparticles on the ordering of block copolymer/nanoparticle composite thin films and will provide a tool in the fabrication of composite thin films. Copyright © 2012 Society of Chemical Industry     

硅化钛薄膜的制备与应用

金属硅化物因其薄膜电阻率低,熔点高,化学性质稳定,在微电子领域具有广阔的使用前景。本文系统地阐述了硅化钛的性质、制备方法(包括自对准硅化物技术及CVD技术)及其应用。对硅化钛在集成电路中的应用进行了重点介绍。     

化学镀CoWP薄膜的制备及磁性研究

利用化学镀的方法制备了CoWP磁性薄膜。研究了施镀时间对化学镀CoWP薄膜矫顽力和饱和磁化强度的影响,并利用场发射扫描电子显微镜(FSEM)、X射线衍射(XRD)和振动样品磁强计(VSM)研究了CoWP磁性薄膜的表面形貌、成分、微结构及磁学性能。结果表明,化学镀CoWP薄膜主要为hcp结构Co相,晶粒大小为2~3μm;随着施镀时间的增加,CoWP薄膜的饱和磁化强度也随之增大,最高达到122emu/g;CoWP薄膜的矫顽力都在250Oe以下。通过计算Kelly-Hankel(δM)曲线,证实了CoWP磁性薄膜中存在交换耦合作用,产生了剩磁增强效应。     

二氧化钒纳米粉体和薄膜的制备技术

通过查阅国内外文献,从不同角度对二氧化钒纳米粉体和薄膜的各种制备方法进行综述,并报道了其相关应用。     

纳米二氧化钛薄膜制备方法研究进展

二氧化钛纳米晶薄膜优异的性能使其成为研究焦点,制备二氧化钛薄膜有着重要的现实意义。介绍了近年来国内外二氧化钛薄膜制备技术的研究进展,主要涉及高活性二氧化钛光催化薄膜的制备(制备方法包括溶胶-凝胶法、丝网印刷法、激光化学气相沉积法、水热结晶法、电泳法等),负载二氧化钛薄膜常用的载体,以及在环境保护等方面的应用研究现状,并指出以后的研究方向。     

Electrically conductive silicon oxycarbide thin films prepared from preceramic polymers

This work focuses on silicon oxycarbide thin film preparation and characterization. The Taguchi method of experimental design was used to optimize the process of film deposition. The prepared ceramic thin films with a thickness of c. 500 nm were characterized concerning their morphology, composition, and electrical properties. The molecular structure of the preceramic polymers used for the preparation of the ceramic thin films as well as the thermomechanical properties of the resulting SiOC significantly influenced the quality of the ceramic films. Thus, an increase in the content of carbon was found beneficial for the preparation of crack-free thin films. The obtained ceramic films exhibited increased electrical conductivity as compared to monolithic SiOC of similar chemical composition. This was shown to correlate with the unique hierarchical microstructure of the SiOC films, which contain large oxygen-depleted particles, mainly consisting of highly graphitized carbon and SiC, homogeneously dispersed in an oxygen-containing amorphous matrix. The matrix was shown to also contain free carbon and to contribute to charge carrier transport between the highly conductive large particles. The ceramic thin films possess electrical conductivities in the range from 5.4 to 8.8 S/cm and may be suitable for implementation in miniaturized piezoresistive strain gauges.     

TiO2薄膜的制备、改性及光催化性能的研究

以铝片为基底,采用阳极氧化法制备氧化铝薄膜作为TiO₂的固定载体。用溶胶-凝胶法制备TiO₂溶胶,通过在氧化铝薄膜载体上浸渍提拉得到TiO₂膜。通过交流电沉积的方法对其掺杂贵金属改性,得到M/TiO₂复合膜。利用紫外-可见光谱法对复合膜进行表征。实验结果表明,利用Al₂O₃可以很好的负载TiO₂溶胶,500 ℃焙烧有利于形成催化能力较好的锐钛矿型TiO₂,掺杂贵金属Ag和Au的TiO₂试样对甲基橙的光催化效果明显优于未掺杂金属的TiO₂试样。     

Direct writing polyvinylidene difluoride thin films by intercalation of nano-ZnO

Polyvinylidene fluoride (PVDF) is a preeminent pyrolytic and piezoelectric polymer. It has been widely studied as an ideal material for wearable flexible sensors or low-power electronic equipment. PVDF/ZnO thin films were prepared by direct writing method, which promoted the ordered arrangement of PVDF molecular chains under the action of electric field and thus improved the crystallinity of the β phase. Meanwhile, the effects of intercalation of ZnO nanoparticles on the crystallinity of PVDF thin films were explored. The results show that appropriate addition of nano-ZnO as nucleating agent can induce the crystallinity of the PVDF film obviously. While the additive amount of nanoparticles was 0.02 wt%, the relative β phase content of the PVDF film can reach 88.92%. Under the double action of adding ZnO nanoparticles and electric field assistance, the dielectric constant of the composite film increases from 6.9 (pure PVDF) to 12.4 (0.03 wt% ZnO) at a frequency of 1 kHz. The d₃₃ value of the film without polarization is up to −9.1 pC/N, the output voltage is increased to 351 mV, and the conductivity of the composite film has been improved.     

Electrodeposition of FeCoNi thin films for magnetic-MEMS devices

The physical properties, including macro and microstructures, film stress, and corrosion resistances, along with the magnetic properties of electrodeposited FeCoNi thin films, which can be later integrated to magnetic-MEMS devices were systematically investigated by varying film composition. Increased Ni content affected both macro and microstructure of electrodeposits, switching from columnar structure to lamellar structure and from body centered cubic (BCC) to face centered cubic (FCC), respectively. The film stress of electrodeposits was increased with increasing deposit Ni content and it was inversely proportional to grain size. The corrosion resistance of films determined by polarization resistance and pitting potential initially improved with increasing deposit nickel content, followed by a maximum at 48 at.% deposit Ni content. After reaching an upper limit, the corrosion resistance slightly decreased with increasing deposit Ni content. The coercivity of FeCoNi alloy decreased when Ni content increased from 0 at.% to 13 at.% which might be due to decrease in grain size. However, from 13 at.% to 48 at.%, coercivity increased, which could be predominately affected by changes in film stress and microstructure. Fe-rich FeCoNi thin films (e.g. 68Fe29Co 3Ni) show good magnetic properties with minimum film stress for magnetic-MEMS actuated in the out-of-plane direction.     

External normal pressure prevents preferential wetting of PS/PMMA blend thin films

Substrate wetting of the component(s) of thin polymer blend films strongly dictates their phase evolution during thermal annealing. In the case of wetting by one component being preferential than the other, a continuous wetting layer at the substrate will form. Here, we report that the preferential wetting of PMMA within a PS/PMMA thin film can be prevented under normal pressure. Moreover, the external pressure drives the PMMA wetting layer at the substrate (or a PMMA cushion layer intentionally placed between the blend film and the superstrate) into the isolated PMMA domains within the blend film. This results in a film morphology normally observed on neutral surfaces, revealing that normal pressure can potentially be used to effectively control the blend film morphology by preventing the hydrodynamic wetting.     

The effects of nitrogenation on the electrochemical properties of nanocrystalline diamond films

The effect of the nitrogenation on the electrochemical properties of nanocrystalline diamond films produced by microwave plasma CVD in CH₄–Ar–H₂–N₂ gas mixtures was studied systematically, using cyclic voltammetry and electrochemical impedance spectroscopy measurements, for the first time. Differential capacitance, kinetic parameters of reactions in [Fe(CN)₆]^3-/4-redox system and potential window were found to be sensitive to the nitrogen concentration in the process gas. With its increase (from 0 to 25%), a transition of the NCD film behavior from “poor conductor” to metal-like character takes place. The heavily N-doped nanocrystalline diamond films have satisfactory electrochemical properties to be used as electrodes.     

TiO2薄膜光催化剂的性能研究

采用溶胶-凝胶法在玻璃管上制备了透明的TiO₂薄膜，并利用XRD、Raman、UV-Vis和XPS技术对薄膜进行了表征。结果表明,在773 K焙烧的TiO₂样品在290～330 nm处的吸收明显强于573 K焙烧的样品。在573 K焙烧的情况下，薄膜基本为非晶态，但却表现出良好的光催化活性，并随着负载层数的增加，薄膜的光催化活性逐渐增加。在573 K以上，随焙烧温度的升高，TiO₂薄膜的光催化活性逐渐降低。     

二氧化锡薄膜的制备和应用研究进展

介绍了近年来二氧化锡薄膜的制备方法和在功能材料中的应用。探讨了各种方法的特点，提出了今后二氧化锡薄膜的发展趋势和应用前景。