AlGaN-based multiple-quantum-well (MQW) heterostructures were irradiated with a pulsed electron beam. Excitation with a beam energy of 12 keV and a beam current of 4.4 mA produced cathodoluminescense at λ=246 nm with a measured peak output power of >200 mW. The emission is dominated by radiative recombination from the MQW up to the maximum tested excitation power density of 1 MW/cm2, as evidenced by unity slope in a double-logarithmic plot of the light output power vs. excitation power density. Monte Carlo simulations of the depth distribution of deposited energy for different beam energies produced good agreement with the measured peak output power vs. beam energy for an assumed carrier diffusion length of ∼200 nm.

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.

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