Thermionic cooling in cylindrical semiconductor nanostructures

The authors analyzed the thermionic cooling efficiency of the cylindrical semiconductor nanostructures. It is shown that due to the reduced emission current from the inner electrode, the cooling efficiency can be enhanced if the outer cylinder is the cold electrode. The threshold voltage for thermionic cooling is lower in cylindrical devices as compared to that in planar devices. The competition between the heat transport by electrons and the heat conduction by phonons is responsible for the efficiency enhancement and the voltage reduction.