50 kV semi-insulating GaAs photoconductive semiconductor switch

A photoconductive semiconductor switch (PCSS) with a gap of 20 mm was fabricated from semi-insulating GaAs. Triggered by a laser pulse with an incident optical energy of 9.9 mJ and a wavelength of 1064 nm, photoconductivity tests of the PCSS were performed at different bias voltages. The peak photocurrent through the switch in pressurized SF6 at 0.2 MPa was 1.1 kA at a bias voltage of 50 kV. The analyses suggest that the closure of GaAs PCSS operating in nonlinear mode is not always due to the fact that the energy has been dumped from the charging system by comparing the charge initially stored in the capacitors and the charge through the switch. The on-state resistance of the switch employing extrinsic photoconductivity is calculated to be 2.71 Ω.