采用碳化硅器件的高效率光伏逆变器研究

采用新型碳化硅结型场效应功率晶体管的光伏逆变器与采用硅IGBT模块的传统光伏逆变器相比,具有开关频率高、体积小、效率高的特点.本文对桥式碳化硅模块的驱动,以及以碳化硅器件组成的单相光伏逆变器的开关特性、开关损耗以及效率进行了理论分析与实验研究.通过实验样机的测试,验证了方案的有效性与优越性.     

氢离子敏场效应晶体管微机温度补偿技术的研究

本文介绍了氢离子敏场效应晶体管的温度特性,分析了敏感膜-溶液间的界面电势差及其温度系数,并采用线性近似法提出了反映溶液pH 值与输出电压、温度和器件常数之间关系的表达式。介绍了一种可以测量pH 值与温度的微机温度补偿系统。采用温度特性已知的标准缓冲液标定常数后,就可对待测液进行测量。标定与测量均可自动进行。研究表明该系统可以在pH 值很宽的范围进行补偿。在pH4.00、6.86与9.20标准缓冲液中,温度由5℃变至45℃过程中,温度造成的误差仅为未补偿时的1/40,相当于0.001PH/℃。     

石墨烯半浮栅场效应晶体管的制备与电学特性研究

基于石墨烯材料的半浮栅场效应晶体管因其非易失性的存储特性而被广泛研究。通过定点转移工艺制备了一种以少层石墨烯为沟道,六方氮化硼作为隧穿势垒层,石墨烯作为半浮栅电荷俘获层的石墨烯场效应晶体管。由于其独特的半浮栅结构,器件的转移特性曲线出现双狄拉克点。对器件转移特性曲线双狄拉克点现象进行了系统理论分析。另外,得到石墨烯浮栅器件的稳定保留特性,在200 s内,器件存储擦除电流差可以维持在20μA左右。所提出的研究有助于实现基于半浮栅结构的二维材料多功能光电子器件。     

双极型晶体管温度特性的Multisim仿真研究

基于Multisim仿真分析,研究了双极型晶体管参数的温度特性。通过数据仿真和曲线拟合得到了双极型晶体管参数温度特性近似方程。分析了2种不同偏置的电压放大电路的温度性能,为掌握电路系统的温度漂移,优化系统性能提供设计依据。     

用于电机的VMOSFET驱动电源

论述采用N沟道VMOS开关管构成的功率步进电动机驱动电源的设计,给出了电源中的斩波限流电路和调频调压电路.实验证明,该新型驱动装置的运行频率、矩频特性、效率等明显优于同类产品.     

IGBT驱动保护电路的设计与测试

在分析了绝缘栅双极性晶体管(IGBT)动态开关特性和过流状态下的电气特性的基础上,对常规的IGBT推挽驱动电路进行了改进,得到了具有良好过流保护特性的IGBT驱动电路.实践应用证明该电路结构简单,使用可靠,易于操作,配合数字信号处理器(DSP)等控制芯片能达到很好的驱动效果.     

碳化硅肖特基二极管仿真模型及其在自动化装置中的应用

根据碳化硅肖特基二极管半导体物理结构,在测量碳化硅二极管特性参数的基础上研究其静、动态性能及计算机仿真模型.针对其低的通态电阻、反向阳断电压高、高频率、存储电荷少的特点,在适合其应用的太阳能最大功率跟踪电路以及作为IGBT器件的续流二极管电路上研究了其反向恢复特性及对电路效率的提高.实验结果验证了模型的准确性与应用的优越性.     

高速开关阀功率驱动特性研究及电路实现

本文对高速开关电磁阀的功率驱动特性进行了研究。结合研究工作，实现了其中的一种高效驱动电路一升压加脉宽调制驱动。驱动方案的设计简单可行，实际运用结果显示其驱动性能良好。     

A new chip-thickness model for performance assessment of silicon carbide grinding

The chip-thickness models, used to assess the performance of grinding processes, play a major role in predicting the surface quality. In the present paper, an attempt has been made to develop a new chip-thickness model for the performance assessment of silicon carbide grinding by incorporating the modulus of elasticities of the grinding wheel and the workpiece in the existing basic chip-thickness model to account for elastic deformation. The new model has been validated by conducting experiments, taking the surface roughness as a parameter of evaluation .     

Microstructural analysis of silicon carbide monofilaments

In the development of monofilaments, a good understanding of the process/property relationships is essential. Transmission electron microscopy (TEM) is a powerful tool but too slow and expensive to be used routinely. Alternative, cheaper techniques have therefore been investigated. The microstructures of three SiC monofilaments (DERA Sigma SM1140+, Textron SCS-6 and Ultra-SCS) and some experimental samples were studied using a combination of TEM, electron microprobe analysis, Raman microprobe analysis, thermo-gravimetric analysis (TGA) and differential scanning calorimetry (DSC). It was found that the Raman technique was complementary to TEM and easily identified the presence of amorphous C and Si. These could not be seen by electron or X-ray diffraction techniques. DSC indicated the presence of free Si in the DERA Sigma SM1140+ monofilament by a distinctive peak at ∼1400 °C. TGA showed the reaction of monofilament components with gaseous species. The Textron SCS-6 and Ultra species lost weight as C was oxidized to gaseous CO. By contrast, the Sigma monofilament gained weight from formation of SiO₂ from the free Si. The separations of the transverse optical phonon peaks in the Raman spectra were correlated with the density of stacking faults in the SiC crystallites. This was similar in all monofilaments. Analysis of the polarization of the Raman scattering gave information on the orientation of crystallites. The crystallites in SM1140+ and SCS-6 were orientated predominantly with the <111> parallel to the radius. Preliminary interpretation of the polarized Raman scattering from Ultra-SCS indicated more than one orientation of crystallite. One possibility was a mixture of <111> and <110> directions parallel to the radius.     

皮秒脉冲隐形切割碳化硅晶圆实验研究

为了实现高速度切割碳化硅（SiC）晶圆,采用自行研制的高能量皮秒脉冲光纤激光器进行了隐形切割实验。依据切片的截面形貌、表面热损伤区和边缘直线度,分析了皮秒激光器的切割结果,并探究了单脉冲能量和扫描速度对切片质量的影响。结果表明,当使用中心波长为1 030 nm、重复频率为100 kHz、单脉冲能量为20μJ、脉冲宽度约为100 ps的皮秒脉冲隐形切割360μm厚度的SiC晶圆时,切片的质量能够满足实际应用要求,且激光的扫描速度可达400 mm/s,相应的切割速度为44.44 mm/s,高于其他相关报道。     

气体放电电源模型的建立及仿真

控制模型的建立对系统的设计有着重要作用,本文详细阐述了气体放电电源的模型建立过程,并通过仿真得到了控制器的参数。     

轻型碳化硅质反射镜坯体的制造工艺

研究了轻型碳化硅质反射镜坯体制造技术,讨论了制备工艺中的关键环节.提出了一种先进的消失模技术用于制备性能更加优异的背部半封闭式轻量化结构.针对制备大尺寸复杂形状陶瓷的难点,研究了SiC陶瓷素坯凝胶注模成型及成型过程中高固相含量低黏度SiC浆料的配置、浆料固化时间控制及大尺寸复杂形状SiC湿坯的液体干燥工艺等.测试分析了...     

The etching behaviour of silicon carbide compacts

A series of microstructural investigations has been undertaken in order to explore the reliability of particular etches in revealing microstructural detail in silicon carbide compacts. A series of specimens has been etched and examined following complete prior microstructural characterization by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffractometry techniques. In particular, the sensitivity of both a molten salt (KOH/KNO₃) etch and a commonly-used oxidizing electrolytic ‘colour’ etch to crystal purity, crystallographic orientation and polytypic structure has been established. The molten salt etch was found to be sensitive to grain boundaries and stacking disorder while the electrolytic etch was found to be primarily sensitive to local purity and crystallographic orientation. Neither etch appeared intrinsically polytype sensitive. Specifically, for the ‘colour’ etch, the p- or n-type character of impure regions appears critical in controlling etching behaviour; p-type impurities inhibiting, and n-type impurities enhancing, oxidation. The need to interpret etching behaviour in a manner consistent with the results obtained by a variety of other microstructural techniques will be emphasized.     

碳化硅衬底超精密加工技术

通过对比不同的加工方法获得最佳工艺:切片采用多线切割或者多线切割与超声切割相结合;磨削采用双面研磨获得较低翘曲度的表面或ELID磨削实现高速、高效、高质量磨削;抛光工艺使用化学机械抛光方法,通过粗抛提高加工效率,精抛提高表面质量,从而获得超光滑表面。分析了碳化硅衬底加工存在的问题并指出超精密加工的发展趋势。     

Microtribology of silicon,oxide, and carbide surfaces

This paper presents an overview of the microtribological properties of silicon oxide, sapphire, and titanium carbide surfaces as well as a self‐assembled monolayer with respect to their application in microsystems. Testing was performed with a reciprocating microtribometer with normal loads in the micronewton to millinewton range. Silicon and titanium carbide balls were used as counterbodies. For silicon oxide, sapphire and a perfluorodecyltrichlorosilane self‐assembled monolayer (FDTS), the microfriction corresponds to the water contact angle when the smoother titanium carbide ball or the relatively rougher silicon ball was used as a counterbody. Microfriction measurements performed on tribopairs of the same material, but having different roughnesses, showed that the friction of the rougher tribopairs is lower than that of the smoother ones. Interestingly, in the microforce regime, reduction in friction was significant and almost as much as when hydrophobic self‐assembled monolayers are applied on smooth surfaces. This investigation showed that comparative microtribological investigations between different material systems can be very challenging due to the fact that comparable roughness values on samples and countersamples are difficult to realize. Copyright © 2006 John Wiley & Sons, Ltd.     

碳化硅中磷含量的测定

采用过氧化钠熔融试样，在0．6～1．2当量的硫酸介质中，磷与钼一铋盐形成三元络合物，以抗坏血酸还原光度法测定碳化硅中磷含量，解决了生产的急需。