非晶硅薄膜晶化方法

多晶硅薄膜由于具有较高的载流子迁移率和良好的光电性能,广泛应用于集成电路及光电器件中,尤其在太阳电池领域引起了广泛关注。多晶材料晶界处会发生载流子的复合,降低载流子寿命。结晶度与晶粒尺寸是多晶硅薄膜取得良好性能的关键因素,直接制备的多晶硅薄膜一般晶粒尺寸较小、晶界较多,所以常采用非晶硅晶化法制备出晶粒尺寸较大的多晶硅薄膜。介绍了几种常见的非晶硅薄膜晶化方法,总结了各种晶化方法的机理和制备的薄膜的物理性质。     

Selective Nanoscale Fabrication with Roughness Reduction of Polycrystalline Silicon by Physically Induced Fluorine Bonds Using Atomic Force Microscope

Polycrystalline silicon (poly-Si) is widely used as a gate layer in integrated circuits, transistors, and channels through nanofabrication. Nanoremoval and roughness control are required for nanomanufacturing of various electronic devices. Herein, a nanoscale removal method is developed to overcome the limitations of microcracks, complex procedures, and time-consuming conventional fabrication and lithography methods. The method is implemented with a mechanically induced poly-Si phase transition using atomic force microscope (AFM). Mechanical force induces the covalent bonds between silicon and fluorine atoms which cause the phase transition of poly-Si. Then, the bond structure of the Si molecules is weakened and selectively removed by nano-Newton-scale force using AFM. A selective nanoscale removal with roughness control is implemented in 0.5 mM TBAF solution after mechanical force (43.58–58.21 nN) is applied. By the magnitude of nano-Newton force, the removal depth of poly-Si is controlled from 2.66 to 21.52 nm. Finally, the nanoscale fabrication on poly-Si wafer is achieved. The proposed nanoremoval mechanism is a simple fabrication method that provides selective, nanoscale, and highly efficient removal with roughness control.     

A carbon-covered silicon material modified by phytic acid with 3D conductive network as anode for lithium-ion batteries

The requirement for silicon-based anode material is growing and has received attentions. Silicon is a promising anode material for lithium-ion batteries due to the high theoretical capacity. However, the high volumetric variability of silicon has led to severe chalking and rapid capacity degradation. To ameliorate these problems, a carbon-covered silicon material with a 3D conductive network structure was prepared employing glucose and phytic acid as carbon sources. When acted as the anode for Lithium-ion batteries, the prepared composite material delivered 1612 mAh/g in the first cycle and approximately 600 mAh/g at 0.1 A/g after 200 cycles. In addition, even at 5 A/g, a high capacity of 503 mAh/g was reached, and when recovered to 0.1 A/g, the capacity of 878 mAh/g was maintained.     

Advances in the fabrication of titanium based composites

Titanium alloy metal matrix composites reinforced with silicon carbide fibre are being evaluated for a range of highly loaded aerospace applications. Although expensive, if used selectively they can have a dramatic effect on performance and weight. The SMC has one of the strongest capabilities in Europe for the development and production of titanium fibre reinforced MMCs. Consisting of the DRA Sigma silicon carbide fibre manufacturing facility, producing fibre on a commercial basis, and the manufacture of titanium alloy MMCs in commercial quantities by the foil fibre route, and at pilot scale using the alternative matrix coated fibre route. In the foil fibre route a filament winding and fugitive binder method is used to produce a range of component shapes with excellent fibre distribution and consistent properties. The matrix coated fibre process is seen to have advantages over the alternative methods and is likely to become an important manufacturing route for titanium MMCs, particularly for exotic high temperature titanium alloys and intermetallics, and for shapes such as rings, tubes and shafts. As no titanium MMCs components have yet reached full production, it is unclear which of these fabrication methods will become commercially viable, if any. But, the choice is likely to be based on cost, availability and product quality.     

A distributed Bragg reflector porous silicon layer for optical interferometric sensing of organic vapor

In this study, we successfully demonstrated the rapid, sensitive, and reversible sensing of organic vapor using a distributed Bragg reflector (DBR) porous silicon (PS) layer. We fabricated the DBR PS layer on a p⁺-type silicon substrate and investigated its reflectance spectra before, during, and after exposure to the different concentrations of various organic vapors. When the DBR PS layer sample was exposed to methanol, acetone, ethanol, and isopropanol vapors, the maximum reflectance peak promptly shifted toward longer wavelengths by about 4.5, 23.2, 26.0, and 38.2 nm, respectively. We determined that the red-shift in the reflectance spectrum could be attributed to the changes in the refractive index induced by the capillary condensation of the organic vapor within the pores of the DBR PS layer. The DBR PS layer showed excellent sensing ability under the different concentrations and types of organic vapors. In addition, a slight hysteresis of the red-shift was observed during repeated exposure to organic vapors at different concentrations. After removing the organic vapors, the reflectance spectrum promptly returned to its original state.     

Compact modeling of amorphous‐silicon thin‐film transistors with BSIM3

Abstract— A novel approach of modeling a‐Si:H TFTs with the industry‐standard BSIM3 compact model is presented. The described approach defines the a‐Si:H TFT drain current and terminal charges as explicit functions of terminal voltages using a minimum set of BSIM3 parameters. The set of BSIM3 parameters is chosen based on the electrical and physical characteristics of the a‐Si:H TFT and their values extracted from measured data. By using the selected BSIM3 model parameters, the a‐Si:H TFT is simulated inside SPICE to fit the simulated I‐V and C‐V curves with the measured results. Finally, the extracted BSIM3 model is validated by simulating the kickback voltage effect in an AMLCD pixel array.     

反应性化学品泄漏扩散的三维数值模拟

多晶硅副产物四氯化硅泄漏后形成重气云,易与水蒸气发生反应,生成四氯化硅、氯化氢和硅酸的混合有毒气云,威胁人类安全,导致严重的生态和环境危害。针对四氯化硅泄漏后形成的重气云的三维大气扩散与反应迁移过程建立了传递转化模型并采用计算流体力学(CFD)进行模拟研究,化学反应模型采用漩涡破碎模型(Eddy-Break-UpModel)。模拟研究了四氯化硅气体与水蒸气反应过程中四氯化硅、氯化氢、硅酸等有毒物质的空间分布与迁移转化情形。四氯化硅受重力作用下沉并向周围扩展,迎风面处的四氯化硅下沉触碰到地面后向上风侧移动,但主体向下风向迁移;生成的毒害性氯化氢覆盖范围较四氯化硅广泛;反应物和生成物在近地面的浓度较大,威胁环境安全;水解反应消耗水分导致脱水效应和反应放热升温,会对该区域生态造成严重危害。研究结果为反应性化学品事故处理提供了依据。     

扩散硅压力传感器的高精度误差补偿算法

扩散硅压力传感器的传输特性受温度影响较大,必须采用某种手段将传感器的输入压力与温度进行解耦,从而实现对压力传感器输出的有效补偿,进而得到准确可靠的压力测量值.文中分析了一般扩散硅压力传感器的误差组成,针对误差提出了一个简单而又高精度的补偿模型,建立了有效算式,最后通过实例验证了算法的正确性,其精度可达到0.1％FS以下.     

Magnetic properties of grain oriented ultra-thin silicon steel sheets processed by conventional rolling and cross shear rolling

A new procedure consisting of the cross shear rolling (CSR) and the subsequent tertiary recrystallization annealing under dry hydrogen atmosphere was developed to produce the grain oriented ultra-thin silicon sheets less than 0.1 mm with high magnetic property performance. For comparison, the conventional rolling (CR) was also used to process the grain oriented ultra-thin silicon steel sheets. The effect of processing parameters on magnetic properties of the grain oriented ultra-thin silicon steel sheets was investigated. With the increase of annealing temperature and holding time, magnetic properties of the sheets processed by both rolling methods reach saturation as the result of the proceeding of the tertiary recrystallization. The thin sheets rolled by CSR did achieve better magnetic properties than those rolled by CR.     

SOI基光学电流传感器的设计与仿真

将光纤与微电子机械系统(MEMS)技术相结合,设计了一种新颖的检测50Hz高压交流电的光学电流传感器(OCS)。用ANSYS软件分析了器件的模态、动态响应与热膨胀特性,并通过Matlab软件模拟了器件的工作性能。模拟计算表明:ANSYS与理论公式得到的结果基本一致;传感器的量程为100~3600A,对于大电流下的灵敏度可达到0.02dB/A,温度变化±50K时传感器相应的测试误差为0.2%。