  We measure the thermoelectric response of Corbino structures in the quantum
Hall effect regime and compare it with a theoretical analysis. The measured
thermoelectric voltages are qualitatively and quantitatively simulated based
upon the independent measurement of the conductivity indicating that they
originate predominantly from the electron diffusion. Electron-phonon
interaction does not lead to a phonon-drag contribution in contrast to earlier
Hall-bar experiments. This implies a description of the Onsager coefficients on
the basis of a single transmission function, from which both thermovoltage and
conductivity can be predicted with a single fitting parameter. It furthermore
let us predict a figure of merit for the efficiency of thermoelectric cooling
which becomes very large for partially filled Landau levels (LL) and high
magnetic fieldse of merit can be estimated which becomes very large for
partially filled Landau levels and high magnetic fields.
