Encapsulated Thermionic Energy Converter with Stiffened Suspension

This paper reports a prototype of a mechanically and thermally robust encapsulated microfabricated thermionic energy converter (μ-TEC). We used conformal sidewall deposition of poly-SiC to form stiff suspension legs with U-shaped cross sections, which increase the out-of-plane rigidity and prevent contact with the substrate during the heating of the suspended emitter—a qualitative improvement over the previously reported planar SiC μ-TECs [1]. Furthermore, we tested the new μ-TECs with both barium and barium oxide coatings. The coatings reduced the work function of the SiC emitter to as low as ~2.14 eV and increased the thermionic current by 5-6 orders of magnitude, which is a key step toward realizing a highly efficient thermionic energy converter. In addition, we have sealed small arrays of μ-TECs using an anodically bonded pyrex wafer.