Control of antisite defect effect of Sb₂Te₃ thin films

We have grown Sb₂Te₃ thin films on CdTe(111)B and GaAs(111)B substrates by the conventional co-deposition method using molecular beam epitaxy. In order to investigate and reduce the antisite defects, we varied the relative ratio of the flow-rates of Sb and Te. X-ray diffraction patterns (θ-2θ scans) of the films show that they are well aligned with their (00.l) axis normal to the substrates, regardless of the relative flow-rate ratio. The measurement of the rocking curves of the films shows that they are of high quality, despite a rather large lattice mismatch between the substrate and the film deposited at 200 °C, with a rocking curve FWHM less than 0.17°. The change in the relative flow-rate ratios of Te to Sb causes a remarkable shift in the temperature-dependent thermopower, resistivity, and Hall coefficient of the films. These results demonstrate that by controlling the antisite defects, Sb₂Te₃ can be a promising thermoelectric material.