C-V法提取SiC隐埋沟道MOSFET沟道载流子浓度

本文对用C-V法提取SiC隐埋沟道MOSFET沟道载流子浓度的方法进行了理论和实验分析. pn结的存在所造成的埋沟MOS结构C-V曲线的畸变为沟道载流子浓度的提取带来一些问题. SiC/SiO₂界面上界面态的存在也会使提取出的数值与实际数值产生偏差. 本文首先从理论上分别分析了沟道深度和界面态对沟道载流子浓度提取结果的影响，然后对两种沟道深度的埋沟MOS结构C-V曲线进行了测试，提取出了沟道掺杂浓度. 在测试中，采用不同的扫描速率，分析了界面态对提取结果的影响. 理论分析结果和实验测 关键词： C-V法 SiC 隐埋沟道MOSFET 沟道载流子浓度     

5-氨基-1,10-菲咯啉：可异构化杂环螯合荧光载体作为比例计量型锌离子荧光探针的一种原型

5-amino-l,10-phenanthroline （5-AP）, as a tautomeric heterocyclic aromatic chelating fluorophore （THACF）, can sense Zn^2＋ selectively by shifting emission from 495 to 564 nm upon Zn^2＋ addition in ethanol. The ratiometric fluorescent sensing behavior has been correlated to the tautomerization of 5-AP affected by solvents and metal chelation. The strategy using THACF as ratiometric fluorescent sensor for Zn^2＋ not only simplifies the synthetic procedure but also gives a promising alternative for Zn^2＋ ratiometric fluorescent sensor design.     

Influence of Triangle Structure Defect on the Carrier Lifetime of the 4H-SiC Ultra-Thick Epilayer

Effect of triangle structure defects in a 180-μm-thick as-grown n-type 4H-SiC homoepitaxial layer on the carrier lifetime is quantitatively analyzed, which is grown by a horizontal hot-wall chemical vapor deposition reactor.By microwave photoconductivity decay lifetime measurements and photoluminescence measurements, the results show that the average carrier lifetime of as-grown epilayer across the whole wafer is 2.59μs, while it is no more than 1.34μs near a triangle defect(TD). The scanning transmission electron microscope results show that the triangle structure defects have originated from 3C-SiC polytype and various types of as-grown stacking faults.Compared with the as-grown stacking faults, the 3C-SiC polytype has a great impact on the lifetime. The reduction of TD is essential to increasing the carrier lifetime of the as-grown thick epilayer.     

环戊烯开环聚合中的高效活化剂——多卤代苯酚

本文研究了苯酚、卤代苯酚和多卤代苯酚对 WCl_6-i-Bu_3Al 催化体系在环戊烯开环聚合中的活化效果。实验结果表明:(1)在苯环上至少有两个取代的氯原子的苯酚在芳烃中才能具有高活化作用;在烷烃中至少要有三个取代的氯原子的苯酚,如2,4,6-三氯苯酚、2,3,4,6-四氯苯酚和五氯苯酚,其活化效果才更显著。(2)在无活化剂或活化效果较差的苯酚和一溴苯酚存在下,溶剂效应次序:氯苯>甲苯(苯)>加氢汽油(庚烷、环已烷);在活化效果高的多卤代苯酚存在下,溶剂效应不显现。(3)比较了三种卤代烷基铝的助催化效果,其助催化活性次序:Et_2AlI>Et_2AlCl>Et_2AlBr。(4)双烯烃对环戊烯开环聚合有一定的调聚作用。在实验条件下聚合物反式链节含量没有明显改变。     

界面态电荷对n沟6H-SiC MOSFET场效应迁移率的影响

针对界面态密度在禁带中的不均匀分布，分析了界面态电荷对n沟6H碳化硅MOSFET场效应迁移率的影响.分析结果显示，界面态电荷使n沟碳化硅器件的场效应迁移率明显降低.并给出了实验测定的场效应迁移率和反型层载流子迁移率的比值与界面态密度之间关系. 关键词： 碳化硅 界面态 反型层迁移率 场效应迁移率     

N型4H-SiC同质外延生长

利用水平式低压热壁CVD (LP-HW-CVD) 生长系统,台阶控制生长和衬底旋转等优化技术,在偏晶向的4H-SiC Si(0001) 晶面衬底上进行4H-SiC同质外延生长,生长温度和压力分别为1550℃和10⁴ Pa,用高纯N₂作为n型掺杂剂的4H-SiC原位掺杂技术,生长速率控制在5μm/h左右.采用扫描电镜(SEM)、原子力显微镜(AFM),傅里叶变换红外光谱(FTIR)和Hg/4H-SiC肖特基结构对同质外延表面形貌、厚度、掺杂浓度以及均匀性进行了测试.实验结果表明,4H-SiC同质外延在表面无明显缺陷,厚度均匀性1.74%, 1.99% 和1.32%(σ/mean),掺杂浓度均匀性为3.37%,2.39%和2.01%.同种工艺条件下,样品间的厚度和掺杂浓度误差为1.54%和3.63%,有很好的工艺可靠性. 关键词： 4H-SiC 同质外延生长 水平热壁CVD 均匀性     

基于改进的压缩式随机游走算法对静态电源/地网的模拟

将随机游走法和等效电路压缩相结合,对静态P/G网(Power and Ground Networks)进行分析.针对一个大规模的电路,在经过多层的参数提取和建模后,得到静态P/G网模型.首先根据网络的规律性,运用等效电路压缩法将原始的P/G网进行压缩处理,然后运用随机游走法求解,最后利用计算得到的化简网络电压值,通过相关的插值公式得到原网络的电压值.实验数据表明,改进的压缩式随机游走法可有效简化网络的复杂性,节省计算时间,计算速度提高到普通随机游走法的两个数量级以上.     

Formation of the intermediate semiconductor larger for the Ohmic contact to silicon carbide using Germanium implantation

By formation of an intermediate semiconductor layer (ISL) with a narrow band gap at the metallic contact/SiC interface, this paper realises a new method to fabricate the low-resistance Ohmic contacts for SiC. An array of transfer length method (TLM) test patterns is formed on N-wells created by P⁺ ion implantation into Si-faced p-type 4H-SiC epilayer. The ISL of nickel-metal Ohmic contacts to n-type 4H-SiC could be formed by using Germanium ion implantation into SiC. The specific contact resistance ρ_c as low as 4.23× 10^-5~Ωega \cdotcm² is achieved after annealing in N₂ at 800~°C for 3~min, which is much lower than that (>900~°C) in the typical SiC metallisation process. The sheet resistance R_sh of the implanted layers is 1.5~kΩega /\Box. The technique for converting photoresist into nanocrystalline graphite is used to protect the SiC surface in the annealing after Ge⁺ ion implantations.     

4H-SiC中基面位错发光特性研究

本文利用阴极荧光(CL)和选择性刻蚀的方法对4H-SiC同质外延材料中基面位错的发光特性进行了研究. 结果表明螺型基面位错(B_TSD)和混合型基面位错(B_MD)分别具有绿光和蓝绿光特性,其发光峰分别在530 nm附近和480 nm附近. 从测试结果中还发现B_MD 的发光位较B_TSD有所蓝移,分析认为B_TSD位错芯附近原子沿伯格斯 关键词： 4H-SiC 基面位错 发光特性 禁带宽度     

窄缝通道内带粗糙面和扰流柱的强化换热实验与热力性能分析

一、前言 窄缝通道实质上是一种高宽比较大的矩形通道,它在涡轮叶片尾部的冷却中,在化工和能源利用等方面有着广泛的应用。大量的研究结果表明,窄缝通道的换热系数和阻力系数要比光滑圆管的低百分之十到百分之二十左右。然而在窄缝中采用各种强化手段后,情形变得比较复杂。在窄缝中加扰流柱不仅可以增加换热还可加强通道的刚性,是一种有效的强化换热手段,文献[3]和[4]对此进行了研究。将通道的内表面粗糙化是另一种强化方