超快响应GaN半导体光导开关的研制

Development of Ultra-Fast Response GaN Photoconductive Semiconductor Switch

半导体光导开关(PCSS)利用半导体材料的高耐压、快速响应与高迁移率等特性,可产生大功率超窄脉冲信号。利用半绝缘GaN材料制备了异面斜对电极PCSS,通过去除芯片侧边金属化合物来减小暗态电阻,提升了PCSS暗态耐压并降低暗态漏电,采用绝缘导热封装提升器件的耐压与可靠性,研制了快拆式测试电路与夹具,实现储能、触发与低寄生同轴输出功能,提升了高频测试准确度与高频响应能力。搭建了高压宽带PCSS测试系统,测量开关线性工作特性,在5 kV偏置电压、触发激光脉冲波长为532 nm、能量为5 mJ下,GaN PCSS在50Ω负载上输出超快脉冲信号电压峰峰值大于2 kV,脉冲信号上升沿小于88 ps。

With the advantages of high withstand voltage,fast response and high mobility of semiconductive materials,the photoconductive semiconductor switch(PCSS)can be used to generate high-power ultra-narrow pulse signals.Semi-insulating GaN material was used to prepare PCSS with oblique counter electrodes.By removing the metal compound on the side edge of the chip,the dark-state resistance of the PCSS is reduced,the dark-state withstand voltage of the PCSS is improved and the dark-state leakage current is reduced.The insulating and thermal conductive package was used to improve the withstand voltage and reliability of the device.A quick-release test circuit and fixture was developed.The functions of energy storage,triggering and low parasitic coaxial output are realized,and the high-frequency test accuracy and high-frequency response capability are improved.A high-voltage broadband PCSS test system was built to measure the linear operating characteristics of the switch.Under the bias voltage of 5 kV,the trigger laser pulse wavelength of 532 nm and the energy of 5 mJ,the peak-to-peak value of the ultra-fast pulse signal output voltage by GaN PCSS under 50Ωload is higher than 2 kV,and the rising edge of the pulse signal is less than 88 ps.