Multiple surface conduction channels via topological insulator and amorphous insulator thin film multi-stacks

Multi-channel Bi₂Se₃ thin films were grown by combining molecular beam epitaxy and atomic layer deposition. High-resolution transmission electron microscope images showed that c-axis oriented Bi₂Se₃ grew on amorphous Al₂O₃ even after multiple stacking. While the surface morphology degraded for the upper layers, each layer was electrically similar. The electrical transport measurements showed that the weak anti-localization effect was quantitatively enhanced upon increasing the number of Bi₂Se₃ channels. Our results provide a promising approach to exploit diverse combinations of layered topological insulator films vertically stacked with amorphous insulator films.