THERMOELECTRIC SIGNATURE OF THE EXCITATION SPECTRUM OF A QUANTUM-DOT

An electon-heating technique has been used to measure the diffusion th ermopower of a quantum dot in the Coulomb blockade (CB) regime. When t he gate voltage defining the dot is swept, the thermovoltage across th e dot oscillates about zero with a period equal to that of the CB osci llations in electrical conductance and with a magnitude consistent wit h a Landauer formulation. In addition, a reproducible fine structure o n top of the CB oscillations in the thermovoltage was observed that ap pears to result from the N-particle excitation spectrum of the dot.