Proximity effects on optoelectronics of Bi₂Se₃

The properties of atomically thin materials are extremely sensitive to the immediate vicinity of their surfaces. While numerous studies have explored this sensitivity, proximity engineering to enhance the properties of atomically thin layered materials has not been thoroughly investigated. Topological insulators (TIs) represent a novel state of quantum matter, distinguished by their electrically insulating bulk interior and robust, conductive surface states. Bi₂Se₃ is a well-known topological insulator due to the strong spin-orbit coupling and time-reversal symmetry. Here, we present how proximity to different dielectrics and magnetic materials alters the photothermal response of a two-terminal Bi₂Se₃ device, as measured by scanning photocurrent microscopy. Our experimental results indicate that proximity engineering can modify the surface states, and breaking the time-reversal symmetry could lead to significant alterations to the photoresponse of the devices. These results indicate that optoelectronics of topological insulators can be controlled and engineered via modfying their immediate surroundings.