Thermionic Electron Sources Based on Microscale Tungsten Filaments on a Glass Wafer

Glass wafers exhibit superior dielectric breakdown strength, improved vacuum sealing properties, and optical transparency when compared with silicon wafers, making them more suitable for applications in on-chip vacuum electronic devices (VEDs). While previous on-chip electron sources were mostly fabricated on Si wafers or substrates, this brief presents wafer-scale fabricated thermionic electron sources (TESs) on a glass wafer by employing microscale suspended W filaments. To enhance thermionic emission performances of the emitters, a layer of Y2O3 is deposited on microscale W filaments, which can significantly increase their emission current at specific power by a magnitude of nearly five orders. Low work function of Y2O3 together with high melting temperature of W enables a single microscale thermionic emitter to exhibit an emission current of up to 7.12 mA and an emission density of up to 89 A/cm2. While on-chip thermionic emitters exhibit degraded stability at poorer vacuum and higher emission current, a closed-loop feedback control technique can effectively stabilize the emission current.