Advanced Silicon Diode Switch for HPRF Systems Navy STTR FY2015.A Sol No.: Navy STTR FY2015.A Topic No.: N15A-T023 Topic Title: Advanced Silicon Diode Switch for HPRF Systems Proposal No.: N15A-023-0016 Firm: Radiation Detection Technologies, Inc. 5015 Lake Elbo Road Manhattan, Kansas 66502-1442 Contact: Steven Bellinger Phone: (785) 532-7087 Web Site: www.radectech.com Abstract: 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. Benefits: A critical aspect of the proposed work is the use of silicon over silicon carbide or III-V systems. Silicon has demonstrated its efficacy in present day transitioned HPRF applications by BAE Systems in the quantities required by the DoD (SiC-, GaAs-, and GaN-based PCSS systems cannot claim the same). While silicon has been discounted for many future PCSS efforts, especially for very-high power applications where higher drift velocity and greater thermal conductivity are needed, the requirements set forth in this solicitation are achievable with silicon. The compatibility of silicon with commercially available laser-trigger Nd:YAG systems offers a significant advantage over the wide-band-gap laser-trigger system needs of alternative materials. The Si-based PCSS approach provides a further advantage in being a solid state, compact solution. There are many user requirements that would be satisfied upon the successful completion of Phase I and Phase II of this project. This switch can be used for all requirements where the switching of state from very-high voltage to low voltage instantaneously is needed to produce pulses; for example high-power RF for directed energy type applications. Return