Power dissipation characteristics of great power and super high speed semiconductor switch

The power dissipation characteristics of pulsed power switch reversely switched dynistors （RSDs） are investigated in this paper. According to the expressions of voltage on RSD, derived from the plasma bipolar drift model and the RLC circuit equations of RSD main loop, the simulation waveforms of current and voltage on RSD are acquired through iterative calculation by using the fourth order Runge-Kutta method, then the curve of transient power on RSD versus time is obtained. The result shows that the total dissipation on RSD is trivial compared with the pulse discharge energy and the commutation dissipation can be nearly ignored compared with the quasi-static dissipation. These characteristics can make the repetitive frequency of RSD increase largely. The experimental results prove the validity of simulation calculations. The influence factors on power dissipation are discussed. The power dissipation increases with the increase of the peak current and the n-base width and with the decrease of n-base doping concentration. In order to keep a low power dissipation, it is suggested that the n-base width should be smaller than 320μm when doping concentration is 1.0×10^14cm^-3 while the doping concentration should be higher than 5.8×10^13cm^-3 when n-base width is 270μm.     

反向开关晶体管结构优化与特性测试

对半导体脉冲功率开关反向开关晶体管 (RSD)的结构进行了优化,在RSD中引入缓冲层,建立器件数值模型并作仿真分析,结果表明:缓冲层结构起到了截止电场的作用,使得器件基区得以减薄,较传统结构RSD阻断电压升高而开通电压降低。针对RSD的特殊工作方式,提出了RSD开通电压、关断时间等关键参数的测试方案并进行了实验测量。进行了RSD大电流开通试验,直径7.6 cm的堆体在12 kV主电压下成功通过峰值电流173 kA,传输电荷32 C。     

两步式放电改善反向开关晶体管开通特性研究

针对大功率半导体开关反向开关晶体管(RSD)由于预充不足造成的非均匀开通缺陷, 在直接预充放电工作电路的基础上, 设计了一种两步式放电工作电路. 根据RSD结构特点理论分析了正常开通所需条件, 并对器件元胞结构进行建模分析, 模型仿真结果表明RSD在窄脉宽预充电流作用下具有更佳的开通性能, 降低了预充阶段基区载流子复合. 两步式放电实验发现第一步放电电流幅值、脉宽对于两步式放电电路的正常工作起决定作用, 而反向预充电流主要作用于RSD第一步放电的正常开通, 降低了预充电路设计难度. 仿真及实验结果均表明两步式放电电路较直接式预充放电电路提高了RSD的均匀开通性能, 这是由于两步式放电显著提高了基区等离子体积累.     

超高速大电流半导体开关实验研究

 利用自行研制的固态半导体开关RSD，采用电容储能方式，研究了RSD的电压响应时间、大电流特性、电流上升率等。在测试RSD的电压响应时间时，得到了25 ns的电压下降曲线。在主电容电压为8 kV时，得到峰值为10.1 kA、脉宽为34 μs、电流上升率为2.03 kA/μs的大电流脉冲。通过调整主电路，在主电容为3 kV时，得到的电流脉冲峰值为8.5 kA、脉宽为2.5 μs、电流上升率为7.2 kA/μs。结果表明，RSD是一种开通快、通流能力强、电流上升率高的大功率半导体开关器件。