高增益螺旋形爆炸磁通量压缩发生器

从爆炸磁通量压缩发生器的工作原理和有效利用炸药能入手，探讨爆炸磁通量压缩发生器运行性能的影响因素和设计制造过程应注意的问题。     

Improved performance of 4H-SiC metal-semiconductor field-effect transistors with step p-buffer layer

An improved 4H-SiC metal-semiconductor field-effect transistors (MESFETs) with step p-buffer layer is proposed, and the static and dynamic electrical performances are analysed in this paper. A step p-buffer layer has been applied not only to increase the channel current, but also to improve the transconductance. This is due to the fact that the variation in p-buffer layer depth leads to the decrease in parasitic series resistance resulting from the change in the active channel thickness and modulation in the electric field distribution inside the channel. Detailed numerical simulations demonstrate that the saturation drain current and the maximum theoretical output power density of the proposed structure are about 30% and 37% larger than those of the conventional structure. The cut-off frequency and the maximum oscillation frequency of the proposed MESFETs are 14.5 and 62 GHz, respectively, which are higher than that of the conventional structure. Therefore, the 4H-SiC MESFETs with step p-buffer layer have superior direct-current and radio-frequency performances compared to the similar devices based on the conventional structure.     

A novel planar vertical double-diffused metal-oxide- semiconductor field-effect transistor with inhomogeneous floating islands

A novel planar vertical double-diffused metal-oxide-semiconductor (VDMOS) structure with an ultra-low specific on-resistance (R_on,sp), whose distinctive feature is the use of inhomogeneous floating p-islands in the n-drift region, is proposed. The theoretical limit of its R_on,sp is deduced, the influence of structure parameters on the breakdown voltage (BV) and R_on,sp are investigated, and the optimized results with BV of 83 V and R_on,sp of 54 mOmega cdotmm² are obtained. Simulations show that the inhomogeneous-floating-islands metal-oxide-semiconductor field-effect transistor (MOSFET) has a superior “R_on,sp/BV” trade-off to the conventional VDMOS (a 38% reduction of R_on,sp with the same BV) and the homogeneous-floating-islands MOSFET (a 10% reduction of R_on,sp with the same BV). The inhomogeneous-floating-islands MOSFET also has a much better body-diode characteristic than the superjunction MOSFET. Its reverse recovery peak current, reverse recovery time and reverse recovery charge are about 50, 80 and 40% of those of the superjunction MOSFET, respectively.     

利用康普顿后向散射产生X光源的研究

 利用高能电子对电磁波的康普顿后向散射可以获得波长短、方向性好的X光辐射,这种具有亮度高、发散角小、光子能量可调等特点的辐射,有很好的应用前景。由于电子对电磁场的散射截面很小,要获得较高强度的辐射,不仅要求很强的电磁场作为散射场,而且要求电子束的亮度高;利用光阴极RF腔注入器及30MeV射频加速器产生的30MeV电子束同Nd:YAG激光光腔中的强光场作用,可以获得较高强度的康普顿后向散射,其波长为0.07~0.14nm,发光本领可以达到2.5×10¹¹光子/s。     

大功率RF 离子源阻抗匹配电路的设计与实现

在大功率RF 离子源中,激励器的作用是产生等离子体,阻抗匹配电路是激励器吸收RF 功率的关键。将激励器等效阻抗视为一个电阻和一个电感的串联,采用了一种由一个RF 变压器并和两个可调电容组成的阻抗匹配电路,给出了视RF 变压器为理想变压器时阻抗匹配电路的分析模型,推导了阻抗匹配时两个可调电容的电气参数。当激励器实验装置使用一个石英玻璃激励器时,搭建了一个阻抗匹配电路,成功地将RF 功率耦合进激励器并产生了等离子体。     

金属-氧化物-半导体器件γ辐照温度效应

研究了金属-氧化物-半导体(MOS)器件在γ射线辐照条件下的温度效应.采用加固的CC4007进 行辐照实验,在不同温度、不同偏压,以及不同退火条件下对MOS器件的辐照效应进行了比 较,发现温度对辐照效应的影响主要是决定界面态建立的快慢.高温下辐照的器件,界面态 建立的时间缩短.根据实验结果对器件阈值电压漂移的机理进行了探讨. 关键词： 金属-氧化物-半导体场效应 辐射效应 阈值电压漂移     

降低适用于高密记录写入磁头的Fe-N薄膜矫顽力的研究

用RF磁控溅射方法,在高功率下制备厚度为2μm的薄膜,当N含量在5.9～8.5;原子分数范围内,形成α′+α″相时,4πMs=2.2T,Hc=58.6A/m,可以满足针对高存储密度的GMR/感应式复合读写磁头中写入磁头的需要.用该方法在不同的本底真空度下制备Fe-N薄膜,发现较高真空下比较低真空下制备的Fe-N薄膜磁学性能要好.P=1000W时,较高真空下制备的Fe-N薄膜的矫顽力为34.8A/m,较低真空下制备的Fe-N薄膜的矫顽力为58.6A/m.AFM测试表明,在功率条件相同情况下,较高真空下制备的Fe-N薄膜表面光滑、平整、起伏小、薄膜致密;而较低真空下制备的Fe-N薄膜,表面粗糙、起伏大、薄膜较疏松、不均匀.     

Influence of structural parameters on the immunity of short-channel effects in grooved-gate nMOSFET

This paper presents the influences of structural parameters on the immunity of short-channel effects in grooved-gate n-channel metal－oxide－semiconductor field effect transistor (nMOSFET) using the simulator PISCES-II. The zero or negative groove-junction depth is beneficial to the improvement of the threshold characters, but there exists a limited range. The doping concentration of both substrate and channel has a significant influence on the threshold characters as well as on the device transconductance. Thus, the variation in these adjustable parameters may help to optimize the device design.     

“ROS管”获1988年国际发明展览金牌奖

<正> 由我校物理系叶安祚教授等人发明的“电阻—氧化物—半导体场效应晶体管”(简称ROS管)在1988年北京国际发明展览会上获金牌奖。ROS管是一种新型的绝缘栅场效应晶体管,其特点是栅极由电阻材料构成,在电阻栅极垂直于源漏联线方向的端线的两端制作了两个欧姆接触电极作为双栅     

铁酸镧纳米晶薄膜制备及其在MOS场效应晶体管气敏元件上的应用

纳米晶固体材料是由粒径小于100nm的微晶颗粒聚集而成的块状或薄膜人工固体,它具有特殊性能。本文采用sol-gel法制备了LaFeO_3纳米晶薄膜,并与集成电路平面工艺相结合,首次研制出了用纳米晶薄膜作为栅控制极的MOS场效应晶体管乙醇敏感元件。