Direct Refrigeration by Electron Field Emission From Diamond Microtips

Abstract

This paper describes a concept for creating high-capacity, direct electrical-to-thermal energy conversion for compact cooling based on electron field emission. Electron field emission involves the transport of electrons that tunnel through a potential barrier. The thermodynamics of field emission have remained relatively unexplored. However, emission from wide-band-gap semiconductors, such as diamond, is known to produce an energy filtering effects such that high-energy electrons possess higher probabilities of emission. Lower energy electrons replace the emitted electrons, and thus, this process can produce a refrigeration effect. The refrigeration capacity is proportional to the emission current density, which is very high for diamond emitters. This high electrical current density implies that high thermal current densities are possible. The present work provides a thermodynamic analysis and energy conversion predictions based on experimental current-voltage data from diamond tip emitters. Energy fluxes in excess of 100 W/cm2 are predicted by the theory for room-temperature operation.