Advanced Silicon Diode Switch for HPRF Systems

Silicon-based photoconductive switch technology, despite its widespread industrial use, has not reached its limit in repetition-rate nor recovery-time. While traditional Si-PCSS systems have demonstrated poor recovery time (tens to hundreds of microseconds), new understanding in absolute photo-carrier generation and the resultant reduced sweepout time, provides one means to get beyond this seemingly fundamental limitation. The proposed work is a mix of research and development. The research aims to find the limits of switch recovery time that go beyond the phase I requirements while the objective of the development effort is to build, test and demonstrate a transition-capable Si-PCSS system that meets the phase I specific requirements. The research and development effort together form the basis to meet the phase II requirements. The effort builds on preliminary results, which show that reduced optical trigger energy per pulse onto a Si-PCSS can reduce recovery time relative to commercially available Si-PCSS systems by at least one order-of-magnitude. Based on these results, the investigators will study, refine and implement the laser energy density (beam size) and laser energy placement onto silicon p-i-n heterostructures as a function of absolute trigger energy, heterostructure type, operational voltage (> 1500-V), and heterostructure aspect ratio.