新型阶梯变掺杂SiC漂移阶跃恢复二极管

A Novel Silicon Carbide DSRD with Variable Doping in Base Region

漂移阶跃恢复二极管(DSRD)一般应用于超宽带脉冲信号源,可以将纳秒级高压脉冲换向负载,这对于输出脉冲的上升前沿有很高的要求。文章提出了一种具有基区变掺杂的新型宽禁带材料漂移阶跃恢复二极管,将传统的基区掺杂变为阶梯式的浓度分布,基区内形成由浓度差导致的内建电场,该内建电场在DSRD放电回路反向泵浦阶段调节载流子分布,并加速载流子抽取。利用Sentaurus TCAD进行了器件电路联合仿真。结果表明,在具有相同峰值的电压情况下,新结构器件的正向注入结束时空穴最大速度较传统结构提升了29%,电压上升率为19.7 kV/ns,较传统结构(15.8 kV/ns)提升了25%。新结构使反向泵浦阶段的时间降低,输出的电压脉冲前沿的上升率更大,且工艺流程只需调节外延时的气体剂量,工艺上可实现。

Drift step recovery diodes(DSRD) are generally used in ultra-wideband pulse signal sources, which can reverse nanosecond-level high-voltage pulse to the load. However, DSRD have high requirements for the rising front edge of the output pulse. A novel wide band gap material step recovery diode with variable doping in the base region was proposed in this paper, in which the doping of the traditional base region would be changed into a stepwise concentration distribution. Built-in electric field was formed by concentration gradient in base region, which would adjust the carrier distribution during the reverse pumping phase of the DSRD discharge circuit and accelerate the carrier extraction. The joint simulation of the device-circuit was performed by Sentaurus TCAD. The results showed that the maximum structure hole velocity at the end of forward injection was increased by 29% compared with the traditional structure, and the voltage rise rate was 19.7 kV/ns, which was 25% higher than the traditional structure(15.8 kV/ns). The proposed structure reduced the time of the reverse pumping stage, and the voltage rise rate of the rising front edge of the output voltage pulse was larger, while the time was shorter. As for the process, only the gas dose of the epitaxial process needed to be changed, which could be realized.