Electrically Tunable Wafer-Sized Three-Dimensional Topological Insulator Thin Films Grown by Magnetron Sputtering

Three-dimensional (3D) topological insulators (TIs) are candidate materials for various electronic and spintronic devices due to their strong spin-orbit coupling and unique surface electronic structure. Rapid, low-cost preparation of large-area TI thin films compatible with conventional semiconductor technology is the key to the practical applications of TIs. Here we show that wafer-sized Bi_2Te_3 family TI and magnetic TI films with decent quality and well-controlled composition and properties can be prepared on amorphous SiO_2/Si substrates by magnetron cosputtering. The SiO_2/Si substrates enable us to electrically tune (Bi_1-xSb_x)_2Te_3 and Cr-doped (Bi_1-xSb_x)_2Te_3 TI films between p-type and n-type behavior and thus study the phenomena associated with topological surface states, such as the quantum anomalous Hall effect (QAHE). This work significantly facilitates the fabrication of TI-based devices for electronic and spintronic applications.