Refrigeration effect in a single-level quantum dot with thermal bias

We theoretically study the heat generation in a quantum dot (QD) connected simultaneously to two reservoirs and a local phonon bath. We find that driven solely by an external thermal bias, the resonant tunneling electrons can absorb heat from the phonon bath to the QD that are held at the same temperature. This QD refrigerator also works well under the thermoelectric effect. At room temperature and large thermal bias, the magnitude of the heat current density is on the order of nW/cm(2) in typical Ge/Si QD, of which the dot diameter is 40 nm with phonon frequency 5 x 10(13) rad/s. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4720093]