Antisite defects of Bi2Te3 thin films

We have successfully grown ${\mathrm{Bi}}_{\mathrm{2}}{\mathrm{Te}}_{\mathrm{3}}$ thin films on CdTe(111)B using molecular-beam epitaxy. Structural and transport properties have been investigated using in situ reflection high-energy electron diffraction, θ–2θ x-ray diffraction analysis, thermopower, and Hall measurements. Both the crystallinity and the transport are found to be strongly affected by nonstoichiometry. The most stoichiometric sample had a high crystallinity, high thermopower, and high electron mobility. However, ${\mathrm{Bi}}_{\mathrm{2}}{\mathrm{Te}}_{\mathrm{3}}$ films with excess Te had a reduced lattice constant, poorer crystallinity, reduced magnitude of the thermopower, and reduced mobility. All of these observations can be explained in terms of antisite defects in which excess Te occupies Bi lattice sites and behaves as a n-type dopant.