<title>High-power stacked Blumlein pulsers commutated by a photoconductive switch treated with amorphic diamond</title>

Abstract

Photoconductive switching of the stacked Blumlein pulsers, developed at the Univ. of Texas at Dallas (UTD), currently produces high power, nanosecond pulses with risetimes on the order of 200 ps. The device has a compact geometry and is commutated by a single GaAs photoconductive semiconductor switch (PCSS) triggered by a low power laser diode array. Filamentation of the conductivity associated with high gain GaAs switches produces such high current density that the switches are damages near the metal-semiconductor interface and the lifetime is limited. The semiconductor properties of amorphic diamond can be employed to improve the PCSS longevity by coating the switch cathode or anode areas or both. For example if the switch cathode is coated, the tunneling of electrons from amorphic diamond to GaAs during the off-state stage of PCSS operation provides pre-avalanche sites that diffuse conduction current upon switch activation. This report presents the progress toward improving the high gain switch operation and lifetime by advanced treatments with amorphic diamond coatings. A significant improvement in switch lifetime is demonstrated by testing the diamond-coated switch performance in a stacked Blumlein prototype pulser.