Vacuum thermionic refrigeration with a semiconductor heterojunction structure

We consider possibilities for refrigeration by emission of electrons into vacuum using a semiconductor layered heterostructure and applying electric field in the order of 106 V/cm. Under the influence of a strong electric field, the height of the vacuum potential barrier is significantly reduced due to the Schottky effect and penetration of electric field into the semiconductor layer allowing high emission current. Joule heating inside the semiconductor layer can be minimized by creating a heterostructure with decreasing electron affinity from the metal–semiconductor boundary to the semiconductor–vacuum boundary. We find it is possible to obtain large Peltier currents while minimizing joule heating in the semiconductor. We find it is realistic to expect cooling of 10–100 W/cm2 at room temperature and down to 100 K by adjusting the thickness, and electron affinities of the semiconductor within practical ranges.