Electrical and optical characterization of Na: CuInS2 thin films grown by spray pyrolysis

The structural, electrical and optical properties of Na-doped CuInS₂ thin films grown by spray pyrolysis were studied. These films crystallized in the sphalerite structure of CuInS₂, and showed to contain traces of indium sulfide and CuIn₅S₈ as impurity phases. All films were In-rich and showed p-type conductivity. The film conductivity was strongly affected by Na-doping, which decreased from 10⁻² to 10⁻⁵ S/cm by increasing the [Na]/[Cu] ratio from 0.005 to 0.03 in the spray solution. The band gap energy was observed to increase, from 1.4 to 1.45 eV, with increasing the [Na]/[Cu] ratio. Our results suggested that Na could be an effective acceptor impurity in sprayed CuInS₂.     

Pulsed electrodeposition and characterization of molybdenum diselenide thin film

Molybdenum dichalcogenides are semiconductors with layered type structure, which can act as efficient electrodes in the realization of photoelectrochemical solar cells. The main advantage of this molybdenum diselenide (MoSe₂) semiconductor is the prevention of electrolyte corrosion because of the phototransitions involving non-bonding d-d orbital of the Mo atoms. Polycrystalline molybdenum diselenide thin films are prepared by pulsed electrodeposition on conducting glass and titanium substrates in galvanostatic mode from an ammoniacal solution of H₂MoO₄ and SeO₂. The growth kinetics of the film was studied and the deposition parameters such as electrolyte bath concentration, bath temperature, time of deposition, deposition current, pH of the electrolyte and duty cycle of the current are optimized. X-ray diffraction analysis of the as deposited and annealed films showed the presence of highly textured MoSe₂ films with polycrystalline nature. EDAX spectrum of the surface composition confirms the nearly stoichiometric MoSe₂ nature of the film. Surface morphology studies by scanning electron microscope (SEM) shows that the films are pinhole free and of device quality nature. The optical absorption spectra show an indirect band gap value of 1.16 eV. Conductivity measurements were carried out at different temperatures and electrical constants such as activation energy, trapped energy state and barrier height were calculated.     

RF reactive magnetron sputtering for Fe-doped titania films deposited from ceramic targets

Fe-doped titania films are prepared by RF magnetron sputtering on Si wafers with specifically designed TiO₂ targets containing different amounts of Fe₂O₃ powder as a dopant source. The physical properties of the films are investigated in terms of the preparation conditions, such as Fe₂O₃ content in the target, RF power, substrate temperature and working pressure. The films show the typical crystallographic orientation. The growth rate increases with increasing RF power, but decreases with working pressure. Films with 40 nm and the transmittance over 90% at the visible region are prepared by using Fe-doped titania target.     

Properties of cu-doped low resistive ZnSe films deposited by two-sourced evaporation

Two-sourced evaporation technique is used to prepare hard ZnSe films by controlling the evaporation rates of both Zn and Se at substrate temperature of 400 °C. The films are doped with Cu by immersion in the Cu(NO₃)₂-H₂O solution for different periods of time. The XRD has not shown a drastic change in the film structure while the electrical resistivity of the deposited film dropped from 10⁹ Ω-cm to about 1.6 Ω-cm for solution immersed films after heat treatment. Optical properties of deposited and doped films, such as film thickness, absorption coefficient and optical band gap have been calculated from the normal transmission spectra in the range of 300-2200 nm.The optical results show a decrease of the transmission and an increase of the refractive index and a slight shift in the optical band gap. Chemical composition of the Cu is determined by using absorption of immersed films. The composition of Cu is also compared with the composition detected by electron microprobe analyzer (EMPA).     

机电一体化技术在采油工具测试站总体方案设计中的应用

利用机电一体化技术可靠性高、使用、调整、维护方便、具有复合功能等优点 ,应用于某油田采油工具测试站总体方案设计 ,包括测试站主要试验装置、计算机测控系统技术方案等 ,提高了测试站测试精度与效率。     

低电压驱动的硅基Ka波段级联式MEMS移相器

通过在共平面波导上周期性地分布微机械电容,外加电压驱动改变电容值,可实现级联式MEMS移相器.本文讨论了优化相移特性对共平面波导特性阻抗及下拉电压的要求,通过工艺参数优化制备了高阻硅基上的Ka波段级联式MEMS移相器,测试结果表明制备器件具有较低的驱动电压,8V时即产生明显的相移量,在36GHz处15V驱动电压时相移量为118°,25V时为286°.对微结构弹性膜的机械振动寿命测试表明,13级级联的MEMS移相器所有弹性膜同步振动的寿命为3×10⁶次.为器件的实用化提供了重要保障.     

正则化广义逆ERT 图像重建算法的研究

提出一种正则化广义逆ERT图像重建算法，利用ERT仿真软件得到的数据进行图像重建。与常用的ERT图像重建算法进行比较，重建出的图像经过统一的门限滤波后，反投影算法、灵敏度系数算法和正则化广义逆ERT图像重建算法重建图像的CSIE平均值分别为12％，9％和6％。研究表明，正则化广义逆ERT图像重建算法重建速度快，能显著提高重建图像的质量，适合于工业过程应用。     

32电极的电阻抗成像系统的设计与实现

提出了一种32电极的电阻抗成像系统。它采用TMS320VC33浮点DSP芯片完成对各个模块的控制功能，使得整个系统具有灵活性强和易将算法移植进去的优点。文章着重介绍了该系统的各个模块，并在最后给出了实验结果。     

全数字化双向DC/DC变换器的分析和设计

分析了电压和电流两种控制模式，基于电流模式提出一种具有恒压、恒流、恒功率控制等多种功能的控制器。详尽阐述了数字控制系统的采样速率、AD转换器位数、DPWM分辨率和开关频率的设计原则，提出了非同步采样检测方法。针对DC／DC变换器强的非线性、时变特性，提出一种新型变参数滞环PID调节器，改善系统稳定性。采用DSP-TMS320F243作为控制核心，设计了一台额定功率为5kW的双向DC／DC变换器装置。实验结果证明，系统性能优良，可有效用于电动汽车等领域。     

基于数据库管理系统的电机设计集成系统软件开发

本文基于电机设计的基本原理 ,采用Access数据库管理技术、面向对象技术、SQL查询语言 ,利用VisualBasic 6.0为工具开发了基于数据库管理系统的电机设计集成系统软件。在实际使用中充分证明 ,该软件操作方便、运行良好、可维护性高 ,软件计算结果比较接近实验值。