硒化锌晶体光学加工中的宏观应力

采用化学-机械加工工艺加工ZnSe晶体器件.用X射线衍射分析技术测定晶体器件在加工过程中宏观应力的变化.结果表明:加工后器件的损伤层厚度接近为零.抛光后的器件和加工前的器件的宏观应力相近,表明用该工艺加工对器件的宏观应力影响小,这对器件的应用非常有利.加工实验表明:选用的工艺参数和抛光液对加工ZnSe晶体器件是成功的.     

Single step electrosynthesis of Cu2ZnSnS4 (CZTS) thin films for solar cell application

The Cu₂ZnSnS₄ (CZTS) thin films have been electrodeposited onto the Mo coated and ITO glass substrates, in potentiostatic mode at room temperature. The deposition mechanism of the CZTS thin film has been studied using electrochemical techniques like cyclic voltammetery. For the synthesis of these CZTS films, tri-sodium citrate and tartaric acid were used as complexing agents in precursor solution. The structural, morphological, compositional, and optical properties of the CZTS thin films have been studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), EDAX and optical absorption techniques respectively. These properties are found to be strongly dependent on the post-annealing treatment. The polycrystalline CZTS thin films with kieserite crystal structure have been obtained after annealing as-deposited thin films at 550 in Ar atmosphere for 1 h. The electrosynthesized CZTS film exhibits a quite smooth, uniform and dense topography. EDAX study reveals that the deposited thin films are nearly stoichiometric. The direct band gap energy for the CZTS thin films is found to be about 1.50 eV. The photoelectrochemical (PEC) characterization showed that the annealed CZTS thin films are photoactive.     

Effect of pulse plating on composition of Sn–Pb coatings deposited in fluoroborate solutions

Galvanostatic pulsed current (PC) and pulse reverse (PR) plating of Sn–Pb coatings onto copper rotating disks from fluoroborate solutions has been conducted to obtain alloy compositions otherwise not achievable by DC plating. PC plating investigated over a wide range of pulse frequencies (20 Hz–200 kHz) and duty cycles produces coatings with compositions that differ only slightly from those obtained by DC plating at the same current density. On the other hand, the use of PR plating can be dramatic, producing Pb contents both well above and below that achievable by DC plating. Varying the frequency from 20 Hz to 200 kHz with the duty cycle and average current density fixed at 80% and 3.78 A dm^–2 yields compositions between 2.5 and 28 wt.% Pb. The Pb:Sn ratio in the deposit is always lower than that in the plating bath when a PR frequency of 20 Hz is imposed, but generally exceeds it at a frequency of 20 kHz. Alloy composition appears to be closely related to the working electrode potential reached during the anodic pulse. A higher frequency leads to less positive potentials during the anodic pulse and shorter anodic pulse times, which may enhance Sn dissolution and enrich the coating in Pb.     

聚苯乙烯球模板辅助电沉积制备多孔片晶ZnO薄膜

以pH值为5.0±0.1的0.5mol/L Zn(NO3)2溶液为电解液,在聚苯乙烯球(polystyrene spheres,PS)模板的辅助下,采用电沉积方法制备了多孔片晶ZnO薄膜。沉积电位为-0.8V和-0.9V,水浴温度为70℃。用扫描电镜观察了ZnO薄膜的表面形貌。用X射线衍射和紫外/可见光分光光度计对薄膜的性能进行了表征。结果表明:沉积电位对薄膜形貌有着显著的影响;多孔片晶ZnO为六方纤锌矿结构;在300~900nm波长范围内透光率较低,并随波长减小呈近似线性降低。此外,对PS模板辅助电沉积制备多孔片晶ZnO薄膜的形成过程进行了讨论。     

脉冲电沉积钴镍合金层微观结构的研究

研究了钴镍合金镀液中Co^2 浓度与镀层中钴含量的关系,并采用XRD,TEM分析了不同钴含量合金镀层的微观结构。结果表明,沉积层中的钴含量随电解液中Co^ 浓度的增大而显著增大,当镀层中的钴含量为69．8％－78．9％（质量分数）时,镀层为面心立方晶格的α－Co相和排六晶格的ε－Co相组成;钴含量低于69．8％时为α－Co相,钴含量大于78．9％时为ε－Co相,钴含量增大,晶粒尺寸明显减小,合金点阵参数增大。     

The effect of heat treatment on the structure and hardness of pulse electrodeposited NiP-WC composite coatings

In the present work pure nickel-phosphorous and nickel-phosphorous composite coatings with WC particles (mean diameter 200 nm) have been produced under both direct and pulse current conditions, from a modified, organic-free, Watts bath. The produced coatings were thermally treated at various temperatures and the structure, morphology and the microhardness of the deposits were examined after each cycle of heat treatment. Imposition of pulse current conditions led to composite deposits with high-incorporation percentage of WC particles in the matrix. Also, the presence of WC particles resulted in coatings with enhanced microhardness values and retarded diffusion phenomena in the deposits during thermal treatment. Annealing of all coatings at 400 °C revealed complete crystallization of the matrix to the phases of Ni, Ni₂P and Ni₃P accompanied by a significant increase of microhardness for all deposits. Further heating at higher temperatures demonstrated a decrease in microhardness of both kinds of deposits. The experimental data proved that it is possible to produce NiP-WC composite coatings under specific pulse current conditions followed by proper thermal treatment that exhibited considerable enhanced microhardness.     

A general deposition method for ZnO porous films: Occlusion electrosynthesis

In this paper, a modified electrodeposition method, occlusion electrosynthesis (OE), was used to prepare ZnO porous films. The processes of OE were similar to those of electrodeposition except the addition of ZnO nanoparticles in electrolyte. The ZnO porous film prepared by OE (OE-ZnO) was highly porous with considerable thickness (55 μm). The quantum dots-sensitized solar cell based on OE-ZnO porous film showed superior photoelectrochemical performance to that based on the ZnO porous film prepared by doctor-blade (DB) method at the suitable concentrations of ZnO nanoparticles in electrolyte, about 16–32 g/L. In addition to the ZnO porous film constructed with ZnO nanoparticles, the ZnO porous film constructed with ZnO nanorods, ZnO/multi-walls carbon nanotubes and ZnO/TiO₂ composite porous films have also been successfully synthesized by OE, which were expected to be widely applied in various fields. The low temperature (60 °C) processes without post treatment made OE more promising for preparing ZnO porous films than DB, especially the ZnO porous films for flexible devices.     

Optimization of chemical and electrochemical parameters for the preparation of n-type Bi2Te2.7Se0.3 thin films by electrodeposition

A 2^3–1 fractional factorial design comprising four runs and three centre points was applied in order to optimize the electrodeposition process to find a compound with the best stoichiometry leading to a Bi₂Te_2.7Se_0.3 thin film suitable for thermoelectric applications. The key factors considered were the deposition potential, the percentage of bismuth and the percentage of selenium in the solution. The Bi^III, Se^IV, Te^IV electrolyte mixtures in 1 M HNO₃ (pH 0), allowed deposition of ternary alloys to be achieved at room temperature on stainless steel substrates. The deposition mechanism was investigated by linear voltammetry. The films were characterized by micropobe analysis, X-ray diffraction, scanning electron microscopy and atomic force microscopy. The XRD patterns of the film show that the as-deposited are polycrystalline and isostructural to Bi₂Te₃. The SEM study shows that the film is covered by crystallites while the AFM image reveals a low level of roughness.     

双向脉冲电沉积纳米晶光亮镍镀层

采用双向脉冲电沉积法,以糖精和1,4-丁炔二醇作为光亮剂,在钢片上获得了光亮的纳米晶镍镀层.通过正交试验确定最佳的脉冲参教为:正向占空比50%,正向脉冲电流密度30A/dm2,正向周期10ms,反向占空比30%,反向脉冲电流密度8A/dm2.纳米晶光亮镍镀层晶粒细致均匀,孔隙率低,平整性好,无裂纹,具有良好的装饰效果.     

cdSe_xTe_(1-x)薄膜电极光溶解性能的研究

用循环伏安法对半导体Cdse_xTe_(1-x)薄膜电池的光溶解性能进行了研究。在1mol/L KCl溶液中测量光溶解产物的阴极还原特性,考察了在多硫化钠,多硫化钾及铁氰化钾溶液中的光腐蚀行为。用此方法还研究了薄膜电极表面的光刻蚀过程和pH的影响,并用X射线光电子能谱分析光刻进行不同时间后,电极表面发生的变化。     

镀锌钝化膜耐蚀性能的研究

简单介绍了新开发的ＣＨ钝化工艺及其特点,用恒电量技术对比测试了ＣＨ钝化工艺形成的经膜和常规钝和化膜,ＣＨ钝化膜的Ｒｐ、Ｒｆ值大,Ｃｄ、Ｃｆ值小;再应用循环伏安法在－１．０２－－１．６８Ｖ范围进行测试,发现ＣＨ钝化膜的循环伏安图经１０次循环后仍与第一次的一样。两种测试说明了ＣＨ钝化膜常规钝化的耐蚀性高。两种电化学测试的结果与其它方法的结果的一致。     

Mg掺杂对Ba0.5Sr0.5TiO3薄膜介电性能的影响

用醋酸盐和钛酸四丁酯为原料,采用sol-gel工艺在Pt/TiO/SiO/Si基片上制备了含有Mg元素的Sr0.5Ba0.5-xMgxTiO3薄膜,其退火处理温度为750℃.通过X射线衍射和扫描电镜分析技术研究了薄膜的相结构和形貌.采用美国HP Angilent 4294A阻抗分析仪测试了以Pt为底电极、Ag为上电极的MFM电容器的介电性能.实验结果表明:掺镁Sr05Ba05.xMgxTiO3薄膜较未掺杂的Ba05Sr0.5TiO3薄膜相对介电常数高、介电损耗低.介温谱表明在居里温度附近发生了弥散型相变,且居里温度有向低温方向漂移的趋势.     

电子束蒸发制备HfO2薄膜的性能研究

用电子束蒸发方法沉积HfO2薄膜,用X射线衍射和透射光谱测定HfO2薄膜的结构特征和光学性能,并测定薄膜的弱吸收和损伤阈值.结果表明:HfO2薄膜在沉积温度为350℃时,达到了较好的结晶程度.在可见光和近红外光区具有很高的透过率;HfO2薄膜的损伤阈值比较高,达到10.5 J/cm2.     

Tunability of optical constants of Se-Ge-Ag thin films based on change in resistivity with temperature for solar cells

Thin films of semiconductor Se₈₀Ge_20-xAg_x (x = 0, 3, 6, 9, 12 and 15 at.%) were deposited by the thermal evaporation technology. Through optical and electrical characterization, the influence of the Ag ratio on the photoelectric parameters of Se–Ge thin film was studied. The X-ray diffraction pattern showed the amorphous nature of the deposited films as well as the polycrystalline state when the films were annealed at the maximum crystallization temperature (415 K), which was determined by the first derivative of the resistivity curve with respect to temperature. The crystallization kinetics of the film was extracted from the electrical analysis by measuring the change in resistivity with temperature. The electrical results of the thin film showed three regions; namely, amorphous, extended (crystalline) and hopping. In the extended and hopping states, the activation energy and pre-exponential factors were calculated. The optical constants, extinction coefficient and refractive index were calculated using the transmittance and reflectance of the grown Se₈₀Ge_20-xAg_x films. The energy gaps of the films were estimated in the strong absorption regions. The changes in the bandgap energy of the film by thermal annealing can help to produce materials with acceptable band gaps for use as absorber layers in solar cell applications. Also, the results provide microscopic insights and studies on the structure, electr-othermal and optical properties of Ag metal-doped GeSe as a back contact of solar cells.     

Influence of pulse plating parameters on the synthesis and preferred orientation of nanocrystalline zinc from zinc sulfate electrolytes

The influence of pulse electrodeposition parameters (current on-time T_on, current off-time T_off, and pulse current density J_p) was investigated on the surface morphology and grain size of zinc electrodeposited from a sulfate bath containing polyacrylamide and thiourea additives. The grain size and surface morphology of zinc deposits were studied by field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM), and the preferred orientation of the deposits was studied by X-ray diffraction. At constant current off-time and pulse current density, the grain size decreased asymptotically with increasing current on-time. In contrast, increase in the current off-time at constant current on-time and pulse current density resulted in grain growth. A progressive decrease of the grain size was observed with increasing pulse current density at constant current on-time and off-time. Nanocrystalline zinc with an average grain size of 38 nm was obtained at a pulse current density of 1200 mA/cm². The crystallographic orientations developed were correlated with the change in the cathodic overpotential, the angle between the preferred oriented plane and the lowest energy of formation plane (0 0 0 2), and the pulse electrodeposition parameters.     

双向脉冲电镀纳米级镍镀层耐腐蚀性能研究

用直流电沉积法制备了普通光亮镍镀层,同时用双向脉冲电镀制备了纳米级镍镀层。用X射线衍射(XRD)、扫描电镜(SEM)等方法研究了镀层的晶粒尺寸、组织结构和表面形貌,通过孔隙率测定、盐雾试验、静态浸泡腐蚀失重试验和电化学方法等测试了镀层的耐蚀性能。结果表明,采用双向脉冲电流制备的纳米级镍镀层的耐蚀性明显优于普通直流镍镀层。     

Microelectrochemical lithography: A method for direct writing of surface oxides

An experimental set-up is presented that allows direct writing on a metal by local anodisation in a confined electrolyte volume. A scanning droplet cell with reference electrode and counter electrode is attached to an automated xyz stage and allows an efficient addressing of a small surface area. An automatic mode investigation of a material under systematic variation of formation parameters such as formation voltage, scan rate and potentiostatic or potentiodynamic formation mode is demonstrated. The influence of these parameters on the oxide film thickness and film properties are discussed. An example for the method of direct electrochemical oxide spot writing is given. The set-up can also be used in a manual mode to address a surface area of interest such as a pit, single grain, grain boundary or intermetallic inclusion.     

Sensitive determination of Cd and Pb by differential pulse stripping voltammetry with in situ bismuth-modified zeolite doped carbon paste electrodes

Here we investigated the analytical performances of the bismuth-modified zeolite doped carbon paste electrode (BiF-ZDCPE) for trace Cd and Pb analysis. The characteristics of bismuth-modified electrodes were improved greatly via addition of synthetic zeolite into carbon paste. To obtain high reproducibility and sensitivity, optimum experimental conditions for bismuth deposition were studied. Voltammetric responses of the BiF-ZDCPEs prepared with different ratios of zeolite, carbon powder, and silicone, were examined under same conditions. The in situ plated (zeolite/graphite powder/silicone, 10/190/80 w/w) BiF-ZDCPEs exhibited the most sensitive response to Cd and Pb in 0.10 M acetate buffer (pH 4.5). The detection limits of the modified electrode were 0.08 μg L⁻¹ for Cd(II) and 0.10 μg L⁻¹ for Pb(II) based on three times the standard deviation of the baseline with a preconcentration time of 120 s under optimal conditions, respectively. The modified electrode showed well linear response to both Cd(II) and Pb(II) over the concentration range from 1.0 to 20.0 μg L⁻¹. The BiF-ZDCPEs were successfully applied to the determination of Cd(II) and Pb(II) in real samples, and the results were in agreement with those of atomic absorption spectroscopy (AAS).     

纳米TiO_2薄膜的结构及紫外可见光谱研究

本文以钛酸丁酯[Ti(OC4H9)4]、盐酸和去离子水为原料,采用溶胶-凝胶法和旋转涂膜工艺,在玻璃基片上制备透明的TiO2纳米薄膜。通过XRD测试表明:经500°C退火得到的薄膜上TiO2为锐钛矿晶相而粉末为锐钛矿、金红石和板钛矿的混合晶相。通过对膜进行紫外可见光谱分析,探讨了影响TiO2纳米膜厚度和禁带宽度的各种因素。实验结果表明:溶胶的陈化时间、膜的热处理温度、涂膜层数等都将直接影响二氧化钛薄膜的紫外可见光谱和禁带宽。     

原位弯曲阴极法测量不同基体上电沉积铜膜和镍膜的内应力

利用直流电沉积法,在碳素钢和铜基体上沉积Ni膜,以及在碳素钢基体上沉积Cu膜。用自行设计的原位弯曲阴极测量装置,测量了不同基体上不同薄膜的内应力。实验表明,原位弯曲阴极法比普通悬臂梁法更精确、简便。薄膜材料的内应力与基体材料有关。碳素钢基体和纯铜基体上沉积的Ni膜内应力随膜厚呈相反的变化趋势。碳素钢基体上电沉积Cu膜的内应力随膜厚的增加而降低;而碳素钢基体上电沉积Ni膜的内应力随膜厚的增加而增大,但当膜厚增大到一定程度时,内应力变化平缓。