Research On Output Characteristics Of GAAS Photoconductive Switches Based Coplanar Intergitated Electrodes Triggered By Femtosecond Laser

With the rapid development in the fields of communications,radar,electromagnetic interference and attack systems and high-power microwave systems,the generation technology of high-power and high-repetition rate ultra-fast electric pulses appears to be particularly crucial.The essence of pulse technology is the energy in time and space compression.Gallium arsenide(GaAs)photoconductive semiconductor switch(PCSS),because of its good output characteristics,is the most potential switch to achieve this technology.There are two main modes of operation for GaAs PCSS,namely,linear and nonlinear.Based on the demand background of high power and high repetition rate,the two operating modes of GaAs PCSS have their own respective deficiencies.When the switch works in the linear mode,the switch can turn off rapidly,but there is no avalanche multiplication phenomenon;nonlinear mode of operation with avalanche multiplication of carriers,but shorter rise time than the linear mode,the required optical excitation is lower,however,the Lock-on phenomenon limits the maximum repetitive operating frequency of the switch,and the high current concentration of the fiaments greatly reduces the life of the switch.In order to investigate the output characteristics of GaAs PCSS with low optical excitation at repetition rate,the distribution of transient electric field in the switch was improved,and the thermal phenomena under the special conditions were analyzed.In this experiment,GaAs PCSS with an electrode gap and width of 5 μm was designed.The entire electrode array is 3 mm,which is suitable for spot coverage.Under the condition that the bias electric field reached k V/cm,while the excitation was of 100 nJ,the effect of the excitation and bias electric field on the output characteristic of GaAs PCSS was investigated.Simulink simulation module in MATLAB was used to simulate the effect of the excitation and electrode gap on its transient output characteristics.Combining with the corresponding physical model,effect of light pulse on switch surface temperature at repeat frequency,heat generation due to dark current and the heat generation phenomenon in the switch conduction condition were preliminary studied.