"Photistors": Optoelectronic Switches

Spire proposes to investigate unique, linear, sensitive, optically triggered, electronic switches that will enable new progress in antenna switching and reconfiguration and in microwave control. Such devices are dual-use technology, desired by both defense and commercial antenna manufacturers. California Microwave, Inc., an antenna company, is actively seeking a practical implementation of such switches, trademarked as "Photistors," for its implementation of a synaptic antenna. California Microwave has identified required switching characteristics, and has encouraged Spire to develop these much needed devices. Photistor-devices are photoconductors made in very pure (background concentration = 10(12) cm-3) , high-lifetime semiconductors. High purity results in extremely high OFF "dark" resistance, while simultaneously allowing a low ON resistance under weak light due to the high material lifetime. Photogenerated carrier concentrations 1000 times higher than the dark background are the goal. Most photoconductors of recent interest use amorphous, semi-insulating, or ion-implanted-precipitate material, which results in lower minority carrier lifetime than pure material. This increases speed and resistivity at the price of decreased sensitivity, higher required optical power, and non-linear IVs. In contrast, Photistor-devices are made in near-perfect semiconductor material to achieve the highest carrier lifetime, light sensitivity, and lowest background concentration (highest OFF/ON ratio) possible with linear I-V curves to avoid harmonic generation by the RF antenna currents. Anticipated Benefits/Potential Applications - Photistor-devices are linear, very light-sensitive, optically triggered electronic switches with applications in antenna switching, antenna reconfiguration, microwave control, high voltage switching, and opto- isolation. Such devices are dual-use technology, and should be very useful to defense and commercial antenna manufacturers and to manufacturers needing control of high voltage equipment.