Refrigeration by combined tunneling and thermionic emission in vacuum: Useof nanometer scale design

We consider new possibilities for cooling by vacuum tunneling. We examine a nanogeometry and find that large cooling currents can be obtained by a com bination of energy selective tunneling of electrons and thermionic emission . The energy selective tunneling is a result of the special form of a poten tial barrier which has wider gap for low energy electrons, which results in electrons above the Fermi level being the principal tunneling component. N umerical calculations show that available material with work functions abou t 1.0 eV are useful for cooling. For gaps of 5-15 nm, which are well within the present state of the art, only a small external voltage (1-3 V) is req uired to create large currents and a useful Peltier coefficient of about 0. 3, and cooling power of 100 W/cm(2). (C) 2001 American Institute of Physics .