Fabrication and design issues of bulk photoconductive switches used for ultra-wideband, high-power microwave generation

The Army Research Laboratory (ARL), in collaboration with the Air Force Phillips Laboratory, has been developing the fabrication process for lateral topology, high-power photoconductive semiconductor switches (PCSS) used in phased-array, ultra-wideband (UWB) sources. This work presents issues associated with the development of these switches. First-generation devices (1.0 cm gap spacing) have been shown to achieve sub-nanosecond risetimes, working hold-off voltages of 50 kV, switched currents of 333 A into a 75 /spl Omega/ load, and lifetimes in excess of 2/spl times/10/sup 6/ shots at 10 Hz. Later-generation devices (0.25 gap spacing) operate at 20 kV and 1 kHz, with improved risetimes, jitter characteristics, and trigger requirements.