反向开关晶体管RSD硅基结构优化与碳化硅基模型研究

发布时间：2018-03-30 14:27

本文选题：脉冲功率　切入点：反向开关晶体管　出处：《华中科技大学》2015年硕士论文

【摘要】：现代脉冲功率技术的发展越来越要求较高的运行频率,来满足其在国防、工业、医疗及环保领域的应用。作为系统中关键技术的开关器件,就更加注重低损耗、大功率、高重复频率和长寿命等器件特性。相比于其他器件,反向开关晶体管(Reversely Switched Dynistor,简称RSD)因采用可控等离子体层换流开通原理而具有均压特性好、通流能力强和较高电流上升率等性能,能较好满足脉冲功率技术对功率开关器件的要求。基于RSD的等离子体双极漂移模型得到的开通电压表达式,可以看出RSD开通时具有较高电压峰值,对脉冲功率系统是不利的。文章分别从Si RSD结构优化和采用新材料(4H-SiC)制作器件两个方面着手,研究如何降低系统中RSD器件的开通损耗。研究单只Si RSD器件的开通电压与阻断电压关系时,实验电路中选取耐压为0.8kV RSD器件和耐压为2.5kV RSD器件进行对比实验,结果表明在相同电压放电下前者最大开通电压显著低于后者。同时,向RSD引入缓冲层来优化器件结构参数进而改善器件的开关特性。采用正交试验设计的方法来评估不同参数缓冲层结构,并选出最优组合。实验对比了耐压2.5kV RSD,结果表明同等条件下带缓冲层结构的开通损耗比传统结构降低了18.96%。在新结构优化特性的基础上,尝试从更基础的新材料进行优化。首次提出采用第三代宽禁带半导体材料Si C代替Si制作RSD器件,并建立数值模型进行具体的仿真研究。采用4H-SiC材料各物理量经验参数值,考虑大注入条件下的典型物理效应,并结合外电路模型对SiC RSD的断态和通态特性进行模拟仿真。仿真数据表明在同等高阻断电压下,Si C RSD比Si RSD具有更好的开通特性。
[Abstract]:The development of modern pulse power technology requires higher operating frequency to meet its application in the fields of national defense, industry, medical treatment and environmental protection. As a key technology in the system, switching devices pay more attention to low loss and high power. Compared with other devices, the reverse switching transistor Reversely Switched Dynistor (RSDs) has the characteristics of uniform voltage due to the controllable plasma layer commutation switching principle. The characteristics of high current passing ability and high current rising rate can meet the requirements of pulse power technology for power switch devices. The on-off voltage expression based on RSD's plasma bipolar drift model is obtained. It can be seen that RSD has a high peak voltage when it is turned on, which is disadvantageous to the pulse power system. This paper starts from two aspects: the structure optimization of Si RSD and the fabrication of devices with new material 4H-SiC. This paper studies how to reduce the switching loss of RSD devices in the system. When studying the relationship between the on-off voltage and the blocking voltage of a single Si RSD device, the experimental circuit selects the voltage-proof device as 0.8kV RSD device and the voltage-proof device as 2.5kV RSD device to carry on the comparative experiment. The results show that the maximum turn-on voltage of the former is significantly lower than that of the latter under the same voltage discharge. The buffer layer is introduced to RSD to optimize the structure parameters of the device and improve the switching characteristics of the device. The orthogonal design method is used to evaluate the structure of the buffer layer with different parameters. The results show that the switching loss of the structure with buffer layer is 18.96 less than that of the traditional structure under the same conditions. On the basis of the optimized characteristics of the new structure, The third generation wide band gap semiconductor material sic instead of Si is used to fabricate RSD devices for the first time, and a numerical model is established for the specific simulation study. The empirical parameters of various physical quantities of 4H-SiC materials are used. Taking into account the typical physical effects under the condition of large injection, and combining the external circuit model to simulate the on-state and on-state characteristics of SiC RSD, the simulation data show that the on-off characteristics of Si C RSD are better than that of Si RSD at the same blocking voltage.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN32

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