Thickness dependence of the thermoelectric voltages in YBaCuO7−δ thin films on tilted substrate of SrTiO3

We report the first measurements of the thickness (d) dependence of the thermoelectric voltages (Vχ) from YBa2Cu3O7−δ (YBCO) films deposited on tilted SrTiO3 (STO) substrate. It was found that the linear relation of Vχ vs. 1/d predicted by the atomic layer thermopile(ALTP) model is followed only at rather thick film region; Instead of a monotonic increase, a maximum of the thermoelectric voltage was measured. A model, which takes the influence of the surface and interface defects into consideration, is put forward and discussed.