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Thin Film Dispenser Cathodes for Thermionic Micro-Devices

Published online by Cambridge University Press:  21 March 2011

Kevin R. Zavadil and
Donald B. King
Kevin R. Zavadil
Affiliation:
Materials and Process Science Center, Sandia National Laboratories Albuquerque, NM 87185-0888
Donald B. King
Affiliation:
Nuclear and Risk Technologies Center, Sandia National Laboratories Albuquerque, NM 87185-0888
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Abstract

Electron emissive thin films that possess the thermionic properties of macroscale dispenser cathodes have been fabricated using standard RF sputter deposition techniques. These films are based on a compositionally modulated structure using W and a Ba-containing ternary oxide. These films exhibit uniform work function values of 1.9 to 2.2 eV with high emission coefficients of 2 to 26 A·cm−2K−2. Electron microscopy shows that W layer coalescence and continued particle growth occurs with prolonged annealing, eventually disrupting the original surface layer. Chemical modification of the oxide during deposition may provide a route to limit the extent of W coalescence and preserve surface metallization layers on these films. These films are designed to be integrated into thermionic micro-devices.

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References

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