Structural and electrical characterization of thin Bi2Te 3 films grown with MBE

Thin Bi₂Te₃ films were grown on Al₂ O₃(0001) substrates with molecular beam epitaxy (MBE). X-ray diffraction (XRD) was used to confirm the orientation and crystalline quality of the films; the c-axis was oriented normal to the film surface. It was found that the full width at half-maximum intensity (FWHM) of diffraction peaks in the XRD pattern depends on the deposition conditions such as substrate temperature and the flux ratio. The reflection high-energy electron diffraction (RHEED) pattern of the deposited films shows a streak pattern at the initial stage of growth. Electrical resistivity, carrier concentrations and Hall mobility were measured in the temperature range from 77K to 300K. The film with narrower FWHM exhibited a lower carrier concentration (5.1×10¹⁹ cm^-3) and electrically intrinsic characteristics around room temperature. For the first time a clear separation of slopes of the Hall mobility in a thin Bi₂Te₃ film is observed. On the other hand, the films with wider FWHM, which have higher carrier concentrations, exhibited a metallic behavior. The electrical properties are closely related to the variation of FWHM of diffraction peaks in the XRD pattern