激光触发能量对横向结构4H-SiC光导开关导通电阻的影响

采用钒掺杂半绝缘4H-SiC衬底,利用磁控溅射在硅衬底上制备了Ni/Au金属电极,并封装加工成同面型横向电极结构SiC光导开关,研究了不同激光触发能量对光导开关光电响应及导通电阻的影响。用波长532nm的激光作为触发源,当激光触发能量从26.7mJ增加到43.9mJ时,光导开关的导通电阻从295Ω降低到197Ω。利用复合理论推导出激光触发时导带中载流子浓度随时间的变化规律,并利用MATLAB模拟计算了不同触发能量下开关的导通电阻,得到了与实验较一致的结果。在此基础上,提出了降低开关导通电阻的两种途径。

Effect of laser excitation energy on resistance of lateral geometry 4H-SiC photoconductive semiconductor switches

The lateral geometry 4H-SiC photoconductive semiconductor switches (PCSS) were fabricated on the vanadium compensated semi-insulating 4H-SiC substrate with the Si (0001) Ni/Au contacts deposited by magnetron sputtering. The effect of laser excitation energy on the photoelectric response and that on the state resistance of PCSS were investigated. The experimental results showed that a nano-second pulse electric signal was obtained when the PCSS was triggered with a 532 nm wavelength laser light. The on state resistance decreased from 295 to 197 when the laser excitation energy increased from 26.7 mJ to 43.9 mJ. Based on the combination theory, the relationship between the carrier concentration and time deduced when the PCSS was irradiated. The on state resistance simulated from the MATLAB is consistent with the experimental results. Finally, the two ways to reduce the on resistance of the switch are put forward.