In this paper, we report low work function mechanically and thermally robust microfabricated thermionic emitters. Conformal deposition of polycrystalline-silicon carbide (poly-SiC) was used to form stiff suspension legs with U-shaped cross sections, which increased the out-of-plane rigidity and helped to maintain a micrometer-scale gap between emitter and collector. The structurally robust poly-SiC suspended structure was coated with a thin tungsten layer to improve adhesion of a work function lowering coating (BaO/SrO/CaO). The measured emitter work function was 1.2 eV and emission current density was >0.1 A/cm 2 , which are promising for applications such as thermionic energy converters.[
2013-0238]Index Terms-Thermionic emitter, thermionic cathode, energy conversion efficiency, barium coating, barium oxide coating, work function lowering, silicon carbide.