Investigation of semi-insulating GaAs photoconductive switches triggered by semiconductor lasers

摘要

The experiment result of semi-insulating GaAs photoconductive semiconductor switch ( PCSS ) with different electrode gaps triggered by semiconductor laser is reported. With the biased voltage of 500V, the semi-insulating GaAs PCSS with 2mm electrode gap is triggered by laser pulse with 5ns pulse width and repetition rate of 15 kHz, then two groups of electrical pulse samples indicate that laser pulse is instable when laser energy is very low. With the biased voltage of 210V, the GaAs PCSS with 0.5mm electrode gap is triggered by the laser pulse in several dozens nanoseconds at 905nm with a repetition rate of 2 kHz. A stable linear electrical pulse is observed. When the energy of the laser increases, the amplitude and the width of the electrical pulse also increase. It indicates that a stable electrical pulse is obtained while laser energy is high. With the biased voltage of 2400V, the GaAs PCSS with 1mm electrode gap is triggered by laser pulse about 100nJ in 40ns at 904nm. The GaAs PCSS switches a electrical pulse with a voltage up to 1700V. Carriers accumulation effect is discussed and the critical value of carriers accumulation effect is given. The relation of the biased voltage, electrode gap and carriers accumulation effect is also discussed. The concentration of deep EL_2 traps in GaAs has a certain effect on nonlinear mode of GaAs PCSS.