Effect of rapid thermal annealing on pentacene-based thin-film transistors

The bottom contact pentacene-based thin-film transistor is fabricated, and it is treated by rapid thermal annealing (RTA) with the annealed temperature up to 240 °C for 2 min in the vacuum of 1.3 × 10⁻² torr. The morphology and structure for the pentacene films of OTFTs were examined by scanning electron microscopy and X-ray diffraction technique. The thin-film phase and a very small fraction of single-crystal phase were found in the as-deposited pentacene films. While the annealing temperature increases to 60 °C, the pentacene molecular ordering was significantly improved though the grain size only slightly increased. The device annealed at temperature of 120 °C has optimal electrical properties, being consistent with the experimental results of XRD. The post-annealing treatment results in the enhancement of field-effect mobility in pentacene-based thin-film transistors. The field-effect mobility increases from 0.243 cm²/V s to 0.62 cm²/V s. Besides, the threshold voltage of device shifts from −7 V to −3.88 V and the on/off current ratio increases from 4.0 × 10³ to 8.7 × 10³.     

Effect of Bi doping on the properties of CdSe thin films for optoelectronic device applications

CdSe and Bi (1%, 2%, 3%) doped CdSe thin films were deposited on the glass substrates using thermal evaporation technique. Effect of Bi doping on the structural, optical, electrical and photo response properties of CdSe thin films were investigated. The X-ray diffraction studies reveals that undoped and Bi doped CdSe films are polycrystalline in nature with hexagonal crystal structure along (002) direction. No significant changes are observed in the lattice parameters or the grain size indicating minimum lattice distortion. The optical band gap of undoped CdSe film was estimated to be 1.67 eV. Replacement of cadmium by bismuth results in an increase in the electrical conductivity of doped films. Doping with bismuth is found to improve the photo sensitivity of CdSe thin films.     

Study of some physical properties of ultrasonically spray deposited silver doped lead sulphide thin films

In this study, undoped and Ag doped PbS thin films at different concentrations were deposited onto glass substrates at 225 °C by using ultrasonic spray pyrolysis technique, in order to investigate the effect of Ag doping on the physical properties of PbS thin films. Structural investigations revealed that all doped PbS:Ag thin films have cubic structure and Ag doping enhances crystalline level of PbS thin films. It was determined that average crystallite size of PbS:Ag thin films increased from 24 nm to 49 nm by increasing Ag doping concentration. Morphological studies showed that surfaces of the films become denser after Ag doping. Optical transmittance and absorption spectra revealed that all deposited thin films have low transmission and high absorbance within the visible region and band gap energy of the PbS:Ag thin films were determined to be in the range of 1.37 eV and 1.28 eV by means of optical method. Electrical conductivity type of PbS:Ag films was determined to be p-type and calculated electrical resistivity was found to be lowest for Ag-doped PbS thin films at 2%.     

Structural, electrical and magnetic characterizations of Ni/Cu/p-Si Schottky diodes prepared by liquid phase epitaxy

In this paper, we have investigated the structural, electrical and magnetic characterizations of Ni/Cu/p-Si Schottky diode prepared by liquid phase epitaxy (LPE). Current density-voltage (J-V), capacitance-voltage (C-V) and capacitance-frequency (C-f) measurements were performed to determine the conduction mechanisms as well as extracting the important diode parameters. Rectifying properties were obtained, which definitely of the Schottky diode type. At low voltages, (0 < V ? 0.4 V), current density in the forward direction was found to obey the diode equation, while for higher voltages, (0.5 < V ? 1.5 V), conduction was dominated by a space-charge-limited conduction (SCLC) mechanism. Analysis of the experimental data under reverse bias suggests a transition from electrode-limited to a bulk-limited conduction process for lower and higher applied voltages, respectively. Diode parameters such as, the built-in potential, V_b, the carrier concentration, N, the width of the depletion layer, W, of the Ni/Cu/p-Si Schottky diode were obtained from the C-V measurements at high frequency (1 MHz). The capacitance-frequency measurements showed that the values of capacitance were highly frequency dependent at low frequency region but independent at high frequencies. The Ni/Cu/p-Si Schottky diode showed magnetic properties due to the effect of Ni in the heterostructure.     

激光处理对油松种子老化的修复效应

用He-Ne激光处理贮存五年的油松陈种子 ,用无离子水浸种 30h后析出液的电导率比CK组低 38% ,其发芽率、活力指数最高可达CK组的 14 6 %和 16 9%。试验结果表明 ,适量的激光处理对油松陈种子的老化有修复效应。     

小型稳压电源的程控化改造

本文介绍了一种采用系统机和单片机对多台小型稳压电源进行集中管理的系统.利用程控方式去设定每一路电源的输出.系统所采用的方法对于电源调节精度要求不高,但数量较多而且相对集中使用的场合具有实际意义.     

电磁随钻测量的电激励模式的分析

本文提出一种电磁随钻测量的电激励模式的分析方法。这一方法可计算电磁随钻测量研究中的重要参数,如地面信号场强分布规律及其与工作频率的依赖关系,发射机构的输入阻抗等,从而为随钻测量系统的总体设计提供基本的依据。用这一方法对试验模型和现场试验进行的计算与试验结果很好符合。     

基于工程化教学模式的电气工程及其自动化专业课程改革探索与实践

本文以工程化教学模式作为电气工程及其自动化(简称“电气”)专业课程的改革方向, 在工程教育专业认证背景下,构建一套理论与实践紧密结合的工程化实践教学体系,激发学生的创新思维和创新意识,使学生成为具有创新精神和实践能力的复合型人才。     

Effects of substrate temperature on electrical and structural properties of copper thin films

This paper addresses the effects of substrate temperature on electrical and structural properties of dc magnetron sputter-deposited copper (Cu) thin films on p-type silicon. Copper films of 80 and 500 nm were deposited from Cu target in argon ambient gas pressure of 3.6 mTorr at different substrate temperatures ranging from room temperature to 250 °C. The electrical and structural properties of the Cu films were investigated by four-point probe and atomic force microscopy. Results from our experiment show that the increase in substrate temperature generally promotes the grain growth of the Cu films of both thicknesses. The RMS roughness as well as the lateral feature size increase with the substrate temperature, which is associated with the increase in the grain size. On the other hand, the resistivity for 80 nm Cu film decreases to less than 5 μΩ-cm at the substrate temperature of 100 °C, and further increase in the substrate temperature has not significantly decreased the film resistivity. For the 500 nm Cu films, the increase in the grain size with the substrate temperature does not conform to the film resistivity for these Cu films, which show no significant change over the substrate temperature range. Possible mechanisms of substrate-temperature-dependent microstructure formation of these Cu films are discussed in this paper, which explain the interrelationship of grain growth and film resistivity with elevated substrate temperature.     

建筑电气工程中低压配电系统的安装与调试

低压配电系统对建筑电气工程是非常重要的,本文对其安装做论述,针对各种建筑物对配电的要求,对系统做合理的调试,最终实现建筑实体安全用电,同时也确保低压配电系统的稳定性。