THEORY OF THE THERMOPOWER OF A QUANTUM DOT

A linear-response theory is presented for the thermopower of a quantum dot of small capacitance. In the classical regime (thermal energy kT much greater than the level spacing DELTAE), the thermopower oscillates around zero in a sawtooth fashion as a function of Fermi energy (as long as kT is small compared to the charging energy e2/C) . The periodicity of the oscillations is the same as that of the previously studied Coulomb-blockade oscillations in the conductance, and is determined by the difference in ground-state energies on addition of a single electron to the quantum dot. In the quantum regime of resonant tunneling (kT much less than DELTAE), a fine structure is predicted to develop on the oscillations. Unlike the Coulomb-blockade oscillations, the periodicity of the fine structure is determined by the excitation spectrum at a constant number of electrons on the quantum dot.