SBIR-STTR Award

Making use of fabrication technology commonly used in the manufacture of liquid crystals and semiconductors, but not previously applied to vacuum devices, the diamond-based backward wave oscillator (BWO) will provide a miniature, energy efficient, electronically tunable and mass producible signal source in the sub mm wavelength regime. Fabricated within a shell of chemically vapor deposited (CVD) diamond, the BWO will employ a novel biplanar interdigital slow wave circuit. The dimensions of the BWO are estimated to be 0.600 inches long and 0.130 inches in diameter at 300 GHz, and a power output of 10 mW is predicted with a total power input of 198 mW for an overall efficiency of 5%. The electron source for the BWO will be a field emission cathode. The offerors have previously demonstrated a diamond field emitter that makes use of the negative electron affinity of diamond to obtain a threshold of emission for a gate voltage as low as 0.25 volts[1, 2]. Widely available, cost effective silicon fabrication technology will be used to integrate the BWO components into a single chip, avoiding conventional assembly techniques. The BWO would replace the present generation of bulky, power consuming signal sources that are unsuitable for space applications. POTENTIAL COMMERCIAL APPLICATIONS Most of the applications of a sub mm oscillator of the type proposed here would be in scientific instrumentation for use in laboratories or in spectroscopy above the earth's atmosphere. If the manufacturing process described in this proposal is successfully developed, relatively inexpensive sub mm oscillators would be available for the first time, which might open up additional commercial opportunities.

The diamond based backward wave oscillator (BWO) proposed here introduces novel slow wave circuit and fabrication concepts and makes use of silicon microfabrication and liquid crystal display technologies that have not previously been applied to the manufacture of vacuum electron devices to provide a miniature, energy efficient, electronically tunable and mass producible signal source in the sub mm wavelength regime. The structure of the BWO is fabricated from a monolithic body of chemically vapor deposited diamond. The technologies of fabrication and design that are proposed here for use in the development of the BWO have been pioneered by the offerors or are readily available from competent vendors. In Phase I a design has been completed for two versions of a 300 GHz oscillator, with 10% and 20% bandwidth, respectively. A fabrication plan has been proposed and a team of credible technical experts has been assembled to carry the work to the demonstration of a prototype oscillator in Phase II.