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 8mm between two electrodes, triggered by 1064nm laser pulses at the 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 energy of 1.9mJ and the pulse width of 60ns, and operated at high voltage of 3 and 5kV. The results show that when the semi-insulating GaAs photoconductive switch operates under an electrical field of 4.37kV/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 20-100ns. 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.