Transport properties of Bi₂(Se_1−xTe_x)₃ thin films grown by molecular beam epitaxy

In this article, the authors report on the growth of the topological insulator alloy Bi2(Se1−xTex)3 by molecular beam epitaxy. A variety of flux ratios and substrate temperatures are used to control the alloy composition. A significant reduction in selenium flux is required to obtain high tellurium-content films. Room-temperature Hall measurements are used to determine the optimal growth window and film composition to obtain low carrier density and high mobility films. Results of the transport properties indicate that all films containing tellurium exhibit worse transport properties than pure Bi2Se3. This is attributed to a defective interface between the film and the substrate acting as the dominant source of carriers, rather than bulk defects.