Development and characterization of diamond-coated photoconductive switches for stacked Blumlein pulsers

The semiconductor properties of amorphic diamond have been employed to improve the photoconductive semiconductor switch (PCSS) longevity by coating the switch cathode or anode areas or both. 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. On the other hand, diamond coating of the switch anode results in increased hold-off characteristics and longer switch lifetimes by blocking the leakage current. In this case the rectifying behavior of the amorphic diamond/GaAs heterojunction operating under reverse bias condition inhibits the conduction until very high fields are reached. This report presents the progress toward improving the high pin switch operation and lifetime in stacked Blumlein pulsers. The switch design options that make optimal use of amorphic diamond coatings for long life operations of avalanche PCSS are given and discussed.