Development of high power photoconductive semiconductor switches treated with amorphic diamond coatings

The semiconductor properties of amorphic diamond can be employed to improve the photoconductive semiconductor switch (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 may diffuse conduction current upon switch activation. On the other hand, diamond coating of the switch anode area may result in increased hold-off characteristics and longer switch lifetimes by blocking leakage current. The critical issue to resolve is the switch design options that make optimal use of amorphic diamond coatings for long life operations of avalanche PCSS in pulsed power devices such as stacked Blumlein. This report presents progress toward improving switch operation and lifetime by advanced treatments with amorphic diamond coatings.