A field enhanced thermionic emitter and its thermionic cooling effect

In this paper thin films of carbon nanotubes (CNTs) are grown on metal foil substrates using plasma enhanced chemical vapor deposition (CVD) technique. The surface of the CNTs is further functionalized by sputter deposition of a thin layer of low-work function barium strontium oxide. The combination of low work function surface coating and high field effect from CNTs resulted in a highly efficient field enhanced thermionic emitter. Strong thermionic emission is observed. The electrons emitted are mostly hot electrons which carried energy away from the emitting surface. A large thermionic cooling effect is observed, and temperature drop as large as 100 °C is achieved on the emitting surface. The detail characterizations of the electron emission properties of these functionalized CNTs including work function measurements are presented. The thermionic cooling effect or temperature drops at various initial temperatures and emission currents is also presented. The potential to use this functionalized CNTs thin film as a micro thermionic cooler is also discussed.