Indium and bismuth interdiffusion and its influence on the mobility in In2Se3/Bi2Se3

Abstract In 2 Se 3 /Bi 2 Se 3 is a promising topological insulator (TI) device structure. However, the (Bi 1 − x In x ) 2 Se 3 thin film system undergoes a transition from TI to band insulator as a function of In concentration, so an investigation of interdiffusion and its influence on transport properties of this system is important. We have grown Bi 2 Se 3 thin films on sapphire (Al 2 O 3 ) using molecular beam epitaxy followed by In 2 Se 3 thin film growth at three different temperatures. Medium energy ion scattering measurements of those films showed that the 50 °C growth temperature resulted in less In diffusion and an amorphous In 2 Se 3 structure. At higher growth temperatures In diffusion was more significant and better In 2 Se 3 crystallinity was observed. Our transport measurements showed that the mobility decreases with increasing In diffusion into Bi 2 Se 3 .