Vacuum Arc Characteristics of CuW70 Alloy

以不同粒度的W粉为原料,采用熔渗法制备CuW70合金,在真空灭弧室模拟电烧蚀实验,通过高速摄影仪和扫描电镜研究CuW70合金表面阴极斑点运动规律。研究结果表明:W粉粒度较小的CuW70合金具有较高的耐电压强度、较长的燃弧时间和低的截留值。W粉粒度较大的CuW70合金真空阴极斑点运动表现为在阳极正下方反复地重复燃烧,并且以选择Cu相击穿为主,烧蚀坑较深;W粉粒度较小的CuW70合金表面阴极斑点在阳极下方出现分裂和偏移,击穿相分布于整个阴极表面。     

微弧氧化电压对钛基氧化膜成分及生物活性的影响

采用微弧氧化法在纯钛表面制备了多孔钛氧化膜并进行表征。室温条件下,采用200V至350V恒压模式以0.5mol/L磷酸溶液作为电解液进行微弧氧化实验。FESEM分析表明,不同电压下,微弧氧化法制备出的氧化膜层均为多孔结构,孔径分布随电压的升高而增大。XRD和XPS分析表明,在强烈的微弧放电过程中,纯钛表面生成了TiO2和TiP2O7,随着电压的增高,TiO2的结晶度和磷元素的含量逐渐升高。体外实验表明,羟基磷灰石的沉积主要归因于样品表面含有大量可分解成HPO24?的TiP2O7,HPO24?离子被吸附到样品表面成核。约4at%磷元素能促进羟基磷灰石的生成。     

Ru对镍基单晶热暴露组织演变及持久性能的影响

对比研究了不含Ru的USTB-F7及添加2.5 wt％ Ru的USTB-F8两种镍基单晶高温合金的组织稳定性和持久性能.标准热处理与1100℃长期热暴露组织研究表明:合金USTB-F7中γ′相形貌介于球形和立方形之间,属中间态形貌;热暴露2000 h后,其形貌仍保持稳定,仅发生粗化而未发生筏排化.Ru的添加使Re元素在γ/γ′中的分配比增大,提高了合金USTB-F8的γ/γ′点阵错配度和γ'相的立方度,从而加速了长期热暴露过程中的筏排化进程,经2000 h热暴露发生了明显的筏排化现象.同时,合金USTB-F7热暴露700 h后在枝晶干处析出了富集Re、W和Cr元素的TCP相,Ru的加入有效地抑制了TCP相的析出,合金USTB-F8直至2000 h仍未析出TCP相.1100℃/140MPa持久性能测试表明,Ru显著提高合金的持久寿命,这与Ru增加合金中的y相体积分数和γ/γ′点阵错配度,促进筏排组织的形成,并减小时效组织中的γ通道宽度有关.     

多孔C泡沫预制体液相渗硅制备C/SiC复合材料研究

以多孔C泡沫为预制体,利用液相渗Si工艺制备了C/SiC复合材料。采用酚醛树脂浸渍-裂解工艺对C泡沫预制体的孔隙率进行调整,考察浸渍-裂解周期对C泡沫预制体孔隙率的影响,研究了C泡沫预制体孔隙率对C/SiC复合材料密度、力学性能、组成和结构的影响。结果表明:预制体孔隙率为72%时制备的C/SiC复合材料性能较好,其密度为2.58g/cm3、弹性模量为81.39GPa,抗弯曲强度为83.88MPa;随着预制体孔隙率的降低,复合材料的密度、弹性模量和抗弯曲强度不断降低,预制体孔隙率的降低影响液相Si充分扩散与C反应,造成复合材料内部存在大量闭孔,这是导致C/SiC复合材料性能下降的主要原因。     

采用浮空场限制环的耐压10kV碳化硅二极管的开发

The design, fabrication, and electrical characteristics of the 4H-SiC JBS diode with a breakdown voltage higher than 10 kV are presented. 60 floating guard rings have been used in the fabrication. Numerical simulations have been performed to select the doping level and thickness of the drift layer and the effectiveness of the edge termination technique. The n-type epilayer is 100 μm in thickness with a doping of 6 × 10^14 cm^-3. The on-state voltage was 2.7 V at JF = 13 A/cm^2.     

CMOS图像传感器钳位光敏二极管夹断电压模型研究

A novel analytical model of pinch-off voltage for CMOS image pixels with a pinned photodiode structure is proposed. The derived model takes account of the gradient doping distributions in the N buried layer due to the impurity compensation formed by manufacturing processes; the impurity distribution characteristics of two boundary PN junctions located in the region for particular spectrum response of a pinned photodiode are quantitative analyzed. By solving Poisson＇s equation in vertical barrier regions, the relationships between the pinch-off voltage and the corresponding process parameters such as peak doping concentration, N type width and doping concentration gradient of the N buried layer are established. Test results have shown that the derived model features the variations of the pinch-off voltage versus the process implant conditions more accurately than the traditional model. The research conclusions in this paper provide theoretical evidence for evaluating the pinch-off voltage design.     

一款采用跨导增强技术的新型宽带低噪声放大器

A new broadband low-noise amplifier （LNA） is proposed. The conventional common gate （CG） LNA exhibits a relatively high noise figure, so active gin-boosting technology is utilized to restrain the noise generated by the input transistors and reduce the noise figure. Theory, simulation and measurement are shown. An implemented prototype using 0.13 μm CMOS technology is evaluated using on-wafer probing. S11 and S22 are below -10 dB across 0.1-5 GHz. Measurements also show a gain of 18.3 dB with a 3 dB bandwidth from 100 MHz to 2.1 GHz and an ⅡP3 of-7 dBm at 2 GHz. The measured noise figure is better than 2.5 dB below 2.1 GHz, is better than 4.5 dB below 5 GHz, and at 500 MHz, it gets its minimum value 1.8 dB. The LNA consumes 9 mA from 1.5 V supply and occupies an area of 0.04 mm^2.     

不同氧化退火工艺下SiO2/SiC界面特性研究

The effect of the different re-oxidation annealing （ROA） processes on the SiO2/SiC interface charac- teristics has been investigated. With different annealing processes, the flat band voltage, effective dielectric charge density and interface trap density are obtained from the capacitance-voltage curves. It is found that the lowest interface trap density is obtained by the wet-oxidation annealing process at 1050 ℃ for 30 min, while a large num- ber of effective dielectric charges are generated. The components at the SiO2/SiC interface are analyzed by X-ray photoelectron spectroscopy （XPS） testing. It is found that the effective dielectric charges are generated due to the existence of the C and H atoms in the wet-oxidation annealing process.     

Study on the sensing characteristics of a local micro-structured long period fiber grating

A simple and effective method employing a local micro-structured long period fiber grating （LMS-LPFG） for the simultaneous measurement of temperature and refractive index is proposed and investigated experimentally. The LMS-LPFG is formed by using the partial etching technique with hydrofluoric （HF） acid in a standard LPFG, in which there are discontinuities in the effective refractive index of cladding modes. Similar to the phase shift theory, a narrow passband and two stopbands are formed. The temperature and the surrounding refractive index （SRI） characteristics of the two stopbands and passband are studied. The temperature sensitivities of the two stopbands and passband are 0.05 nm/℃ approximately. The SRI sensitivity ofpassband （-61.56 nm/RIU） is bigger than that of the two stopbands （-35.62 nm/RIU）. Thus, with the sensitive matrix, we can simultaneously measure the changes of temperature and refractive index.     

Morphological Stabilization by Supramolecular Perfluorophenyl‐C60 Interactions Leading to Efficient and Thermally Stable Organic Photovoltaics

A new PC₆₁BM‐based fullerene, [6,6]‐phenyl‐C₆₁ butyric acid pentafluorophenyl ester (PC₆₁BP^F) is designed and synthesized. This new n‐type material can replace PC₆₁BM to form a P3HT:PC₆₁BP^F binary blend or serve as an additive to form a P3HT:PC₆₁BM:PC₆₁BP^F ternary blend. Supramolecular attraction between the pentafluorophenyl group of PC₆₁BP^F and the C₆₀ cores of PC₆₁BP^F/PC₆₁BM can effectively suppress the PC₆₁BP^F/PC₆₁BM materials from severe aggregation. By doping only 8.3 wt% PC₆₁BP^F, device PC₆₁BP^F651 exhibits a PCE of 3.88% and decreases slightly to 3.68% after heating for 25 h, preserving 95% of its original value. When PC₆₁BP with non‐fluorinated phenyl group is used to substitute PC₆₁BP^F, the stabilizing ability disappears completely. The efficiencies of PC₆₁BP651 and PC₆₁BP321 devices significantly decay to 0.44% and 0.11%, respectively, after 25 h isothermal heating. Most significantly, this strategy is demonstrated to be effective for a blend system incorporating a low band‐gap polymer. By adding only 10 wt% PC₆₁BP^F, the PDTBCDTB: PC₇₁BM‐based device exhibits thermally stable morphology and device characteristics. These findings demonstrate that smart utilization of supramolecular interactions is an effective and practical strategy to control morphological evolution.