The thermo-electromotive force of an N-type thermoelectric material: Assessment of the contribution due to the presence of minority carriers

The role of minority holes in the thermo-electromotive force (thermo-E.M.F.) of a non-degenerate N-type semiconductor in the stationary state and when the quasi-neutrality condition is fulfilled is investigated in this work. The main motivation is to figure out how to reduce its negative effects on the total thermo-E.M.F. of that type of semiconductor. It is shown that there are two different ways to reduce the contribution due to minority carriers: by decreasing the length of the sample or by limiting the surface recombination on the surfaces of the semiconductor. The calculation done in the case of N-type silicon reveals a low contribution of minority holes to the total thermo-E.M.F. of that material but, that contribution increases with the length of the sample and the surface recombination rate toward a limite value.