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关键词： QC小组   变压器   投标   标书  

摘要： QC小组活动作为企业质量管理的改进方式,可持续为企业改进产品质量,提高企业竞争力。文章梳理了某公司变压器标书制作过程中存在的3个问题,指出这3个环节是拖延变压器标书制作时间的关键节点,并提出利用QC小组活动进行效率提升的具体构想。应用文章提出的QC小组活动方案,将能有效提高变压器产品的投标效率。

关键词： 电子辐照加速器   返波型加速结构   磁耦合   等梯度   Marx发生器   固态调制器  

摘要： 针对产业的快速发展及用户端对辐照加速器提高单位产能、节约成本、丰富功能性等方面的迫切需求,研制一款新型高功率、高效率且电子束可调的电子辐照加速器系统。首先引入了等梯度返波管的设计概念,对缩短建场时间、降低功率反射和提升加速结构分流阻抗以及解决束流崩溃问题进行了探索和研究,采用了HFSS对返波加速管进行了3维电磁场仿真,并制造了加速管实物。大功率固态调制器采用Marx发生器形式,采用零电流开关(zero current switch,ZCS)充电,结合FPGA控制绝缘栅双极晶体管(insulate-gate bipolar transistor,IGBT)形成脉冲高压。最终以返波加速管为核心,匹配微波系统、扫描系统、固态脉冲调制器系统等,完成了辐照加速器系统的研制。测试结果表明,系统能量为10.28 MeV,一般工况的功率为24.672 kW,最大功率为28.4 kW,满足设计要求。直线返波加速管配合大功率固态调制器研制的辐照加速器系统技术方案可行,形成的产品实现应用,为电子束辐照技术的发展提供了有力的支撑。

关键词： Normally-off   GaN MOSFET   Enhancement-mode (E-mode)   Selective regrowth technique (SRT)   Selective area regrowth (SAG)   And AlGaN  

摘要： A normally-off GaN MOSFET is successfully fabricated by using the selective regrowth technique (SRT) with regrown AlGaN layer on source/drain (S/D) region. The GaN MOSFET with regrown AlGaN layer and Lg of 10 mu m shows enhanced electrical performance such as maximum drain current (ID,max) of 57 mA/mm, maximum transconductance (gm,max) of 11 mS/mm, and field-effect mobility (mu FE) of 59 cm2/V & sdot;s, respectively, compared to the GaN MOSFET with n+-GaN selective regrowth in S/D region. This is because of the high 2DEG density formed by AlGaN/GaN heterojunction in S/D region. Moreover, to accommodate the poor structural quality of the narrow region regrowth of AlGaN layer on the S/D region, wide regrown AlGaN layer is applied to the GaN MOSFET. Especially, the off-state breakdown voltage improves from 25 V to 192 V with the improved structural quality of wide regrown AlGaN layer and optimized structure and the application of the 70-nm thick SiO2 passivation. These result shows that GaN MOSFET with wide regrown AlGaN layer on S/D region is beneficial to achieving high-quality and uniform normally-off GaN MOSFETs with excellent electrical performance.

关键词： Temperature measurement   MOSFET   Junctions   Transient analysis   Switches   Logic gates   Silicon carbide   Aging   gate-oxide degradation   junction temperature   reliability   silicon carbide (SiC)   switching transient   temperature-sensitive electrical parameter (TSEP)  

摘要： This article puts forward a novel online method to measure the junction temperature (T-j) of silicon carbide (SiC) mosfets. In this method, the voltage spikes in the common source stray inductance are captured to obtain the turn-on and turn-off switching transients of SiC mosfets. The switching transients contain useful information pertaining to the temperature and are used to extract the junction temperature. By measuring both turn-on and turn-off switching transients, the technique effectively addresses the impact of aging on the online junction temperature measurement procedure. The proposed method enables the measurement of junction temperature without high-bandwidth current sensors. In order to improve precision, this approach converts the measured voltage spikes into digital signals with specific pulse width, which can be measured by high-resolution capture module in the microcontroller with an error of less than 1 degree celsius. Importantly, the proposed circuit has minimal impact on the normal operation of the converter and can be integrated into the gate driver integrated circuits (ICs). The effectiveness of this method is validated through experiments conducted on a double-pulse test setup and buck converter. The results confirm the practicality and viability of this approach.

关键词： Circuits   Logic gates   Multivalued logic   Memristors   Inverters   MOSFET   Power demand   Balanced ternary logic   memristor   multi-valued logic   combinational logic circuits  

摘要： Balanced ternary digital logic circuits based on memristors and MOSFET devices are introduced. First, balanced ternary minimum gate TMIN, maximum gate TMAX and ternary inverters are designed and verified by simulation. Next, logic circuits such as ternary encoders, decoders and multiplexers are designed using these three basic gates. For further validation, a ternary 3-1 encoder was hardware-implemented successfully using in-house fabricated memristors and MOS transistors. Two different design approaches, namely the decoder-based method and the multiplexer-based method are introduced and applied to realize combinational logic circuits such as balanced ternary half-adder, multiplier, and numerical comparator. We simulate the circuits using 50nm CMOS technology parameters and BSIM models and present comparisons and analyses of the two design methods in view of the power consumption and component device counts, which can guide subsequent research and development of integrated multi-valued logic circuits. The decoder-based method has advantages both in terms of component numbers and power consumption, but the multiplexer-based method has the advantages of being based on a simple operating principle and ease of implementation.

关键词： Silicon carbide   Mathematical models   Interface states   Semiconductor device modeling   Threshold voltage   Logic gates   Electric potential   4H-silicon carbide (SiC)   interface states   MOSFET   quasi-Fermi level   short channel effects (SCEs)   source contact resistance  

摘要： The poor interface of silicon carbide (SiC)/SiO2 combined with the short channel effects (SCEs) and source contact resistance, collectively impacts the effective threshold voltage in SiC MOSFETs. In this work, a physical discrete channel model was proposed to analyze the influence of the combined effects of varying channel lengths, as well as applied drain and gate voltages. The proposed model was validated through TCAD simulation and by the fabricated SiC power MOSFETs. This model was applicable to MOSFETs with both symmetric and asymmetric channels considering various interface state density distributions. The influence of these factors on effective threshold voltage was also discussed considering variations in source contact resistance and channel doping concentration. Through the analysis of the model results, it was found that the interface states significantly impact the effective threshold voltage through different mechanisms while the SCEs are mitigated by the unsaturated interface states.

关键词： Frequency spectrum   junction temperature monitoring   power loop inductance   SiC MOSFET   temperature-sensitive characteristic  

摘要： Turn-on change rate of drain current di(DS(on))/dt is an electrical parameter suitable for online monitoring of junction temperature in SiC MOSFETs. In practical application, the change of the external circuit will change the temperature-sensitive characteristic of di(DS(on))/dt . In this article, SiC MOSFET in Buck converter is taken as the research object. First, the influence of power loop inductance on di(DS(on))/dt temperature sensitivity of SiC MOSFET is analyzed theoretically. Second, the relationship between the di(DS(on))/dt of SiC MOSFET and the turn-off oscillation frequency of the drain-source voltage is established through the frequency spectrum of switching waveform with ringing. Based on theoretical and experimental studies, a method to modify the temperature-sensitive characteristic of di(DS(on))/dt by turn-off oscillation frequency of drain-source voltage is proposed. The results show that the calibration method can largely eliminate the junction temperature monitoring error caused by the variation of the power loop inductance, and the maximum measurement error decreases from 100 C-degrees to 11.3 C-degrees after correction.

关键词： Carrier scattering   mobility   MOSFET   ultra-thin-body (UTB) Ge-OI  

摘要： The mobility scattering mechanisms in the ultra-thin-body (UTB) Ge-OI p- and n-MOSFETs have been systematically investigated. It is found that the E-eff(-2) dependence is confirmed for the hole mobility in Ge-OI pMOSFETs, while the electron mobility exhibits an unusually strong dependence on E eff (proportional to E-eff(-4)). The mu (ph) exhibits an E-eff(-0.3) dependence for both holes and electrons, along with a temperature dependence of similar to T-1.8. The mu (total) is measured at different depletion layer carrier densities (N-depl), revealing that mu (Coulomb) increases with the rise of N-depl. Specially, mu (Coulomb) exhibits N-depl(0.5) and N-depl(1.8) dependencies for electrons and holes, respectively. Consequently, more pronounced mobility degradation has been confirmed in UTB Ge-OI nMOSFETs than in UTB Ge-OI pMOSFETs. These findings suggest universal carrier scattering mechanisms for both holes and electrons in UTB Ge-OI channels, which are valuable for understanding carrier transport in thin-channel Ge devices for future advanced technology nodes.

关键词： Wireless energy harvesting   Quantum well channel   Ge   Rectification efficiency  

摘要： Wireless energy harvesting is an important application of microwave wireless energy transmission system, but due to the weak energy of RF signals in the 2.45 GHz band, its rectification efficiency is not ideal. As one of the core rectifier components of wireless weak energy harvesting system, the performance of MOSFET determines the rectification efficiency of the system, and its optimized design to improve the rectification efficiency is an important direction of current research in the field. In view of this, this paper proposes and designs Ge quantum well channel PMOS for wireless weak energy harvesting at 2.45 GHz, aiming to improve the rectification efficiency of wireless weak energy harvesting systems. Starting from adjusting the structural physical parameters of the MOS tubes, the absolute value of the threshold voltage is reduced in the weak energy density region, which in turn improves the rectification efficiency of the device. Then, the novel diode connection with the introduction of substrate bias effect is compared with the conventional connection using an ADS simulation circuit, and the simulation results show that the leakage current is smaller and the rectification efficiency is higher under the novel connection. On this basis, a Ge quantum well channel PMOS device is proposed. Compared with the Ge surface channel, the hole mobility of the quantum well channel will be greatly improved, and its rectification efficiency can also be improved. The device is connected to the rectifier circuit with a novel connection and simulated using Silvaco's Mixedmode module. The results show that the rectification efficiencies of the Ge quantum well channel MOS reach 13.53 % and 32 % at low input powers of -20.34 dBm and -6.28 dBm, respectively, which are 3.3 and 1.14 times higher than those of the conventional surface channel MOS.

关键词： 禁带  

ISBN: (纸本)9787111763178

摘要： 本书是国外学者们对宽禁带半导体封装技术和趋势的及时总结。首先，对宽禁带功率器件的发展趋势做了总结和预演判断，讲述宽禁带功率半导体的基本原理和特性，包括其独特的物理和化学属性，以及它们在极端环境下的潜在优势。接着介绍封装材料的选择和特性，分别就互连技术和衬底展开论述，同时，介绍了磁性材料，并对不同材料结构的热性能，以及冷却技术和散热器设计进行了介绍。然后，考虑到功率器件的质量必须通过各种测试和可靠性验证方法来评估，还介绍了瞬态热测试的原理和方法，同时阐述了各种可靠性测试的机理和选择动机。最后，就计算机辅助工程模拟方法列举了许多经典案例。通过本书的学习，读者可以建立起宽禁带功率半导体器件封装的全面概念，为进一步深入研究打下基础。