High gain lateral semi-insulating GaAs photoconductive switch triggered by 1064 nm laser pulses

We report on the experimental results of a lateral semi-insulating GaAs photoconductive switch, with a gap of 8 mm between two electrodes, triggered by 1064 nm laser pulses at a wavelength beyond the GaAs absorption edge. Both the linear and nonlinear modes of the switch were observed when it was triggered by light pulses with an energy of 1.9 mJ and a pulse width of 60 ns, and operated at high voltages of 3 and 5 kV. The results show that when the semi-insulating GaAs photoconductive switch operates under an electrical field of 4.37 kV/cm, it will enter into the linear mode first, and then the switch will undergo the nonlinear mode (lock-on) after a delay of about 20 - 100 us. It is worth noticing that the delay time under high light energy is longer than that in the low optical energy. The non-intrinsic absorption mechanism is discussed. EL2 deep level defects and double-photon absorption in GaAs may play a key part in the absorption process.