Thermoelectric power in very thin film thermocouples: Quantum size effects

The thermoelectric power S-F of thin film thermocouples is related to the bulk thermopower S-bulk by Delta S-F(t)=S-bulk-S-F as a linear function of 1/t when t >> l, where l is the electron mean free path and t the film thickness. For these conditions quantum size effects (QSEs) are negligible. However, when t < l QSEs become relevant. In recent work we have shown that for Pt/Au thermocouples with film thickness t < l(Pt)approximate to 10 nm, Delta S-F(t)=0.194+26.7(1/t)-93.6(1/t)(2)+112.0(1/t)(3). Here we show that this nonlinear 1/t behavior is due to QSE.