Research On Large Current GaAs Photoconductive Semiconductor Switches Triggered By Low Light Of Micro Joule Magnitude

GaAs photoconductive semiconductor switch is regarded as a promising pulse-power device for the outstanding properties,such as simple structure,low optical trigger energy,low timing jitter,high breakdown voltage,large current,and so on.Nowadays,it has been widely used in many domains such as pulse forming,high speed electronics,and the generation of terahertz radiation.However,the application of GaAs PCSS requires it to be solid-state,compact,and low-cost.It is necessary to utilize the compact light source such as a laser diode instead of the desktop laser for GaAs PCSS triggering.The light energy of laser diode is generally in a magnitude of micro joule.The GaAs PCSS will operate in the nonlinear mode.The threshold electric field across the switch is a certain value of 3.2-4.2 kV/cm in GaAs.In this case,a photon excites more than one electron-hole pair caused by the avalanche multiplication process,only under the condition of the avalanche breakdown voltage.Therefore,the possibility that GaAs PCSS is triggered by low light of several micro joules and outputs a large current will achieve.In this paper,for the experiment that low-light triggered GaAs PCSS to generate a strong current pulse,we proposed a RLC transient circuit model of the CM test circuit,and analyzed it to get that this test circuit would make under-damped discharging.We derived the inductance formula of the circuit system,and calculated that the value of the system inductance was about 350nH.The 2 mm gap PCSS delivered a 1.45 kA,250 ns current under a bias voltage of 6 kV,when illuminated by a commercial laser diode.The laser diode had the ad vantage of compact,low cost,and batch manufacturing and was with the output energy of 4 μJ.Combined with the photo activated charge domain(PACD)theory and RLC transient circuit model,we analyzed the reason that the switch had no lock-on effect.It meant that an inexpensive compact PCSS package was promisingly used in high power pulse source,such as firing sets,high-power trigger generator etc.At the same time,we discussed the effect of the storage capacitance on the output electrical output current was.In addition,we studied fast discharge characteristics of different kinds of storage capacitors using the gas spark switch conducting discharging,and concluded that compared with ceramic capacitors,pulse capacitors discharged faster and more completely.