Near-infrared photodetection based on topological insulator P-N heterojunction of SnTe/Bi2Se3

Abstract

Heterostructures constructed from topological insulator materials have aroused great research interests because of their various and unusual features and functions. Growth of topological insulator heterostructures can create a topological p-n junction at their interfaces with robust built-in potential barrier, which helps to improve the photodetection performance of topological insulators. Herein, the high-quality topological insulator SnTe/Bi2Se3 heterostructures were prepared via a two-step physical vapor deposition process. A robust topological p-n junction was confirmed to exist on the heterointerface with a large forward-to-reverse current ratio exceeding 700. Near-infrared photodetector was then fabricated by using of the heterostructure, which presents a ultrafast and steady response to the incident 1550 nm light even under self-powered mode. Note that the photodetector can exhibit a higher light responsivity of 145.74 mA W−1, a maximum detectivity of 1.15 × 1010 Jones, as well as a microsecond (6.90 μs) response speed. The demonstrated SnTe/Bi2Se3 heterostructure devices open up an exciting field for low-power and low-cost optical detection application and great potential of ultrafast memory devices. This novel heterostructure not only takes advantage of the efficient light absorption of topological insulators, but also provides an ideal platform to investigate the energy-band coupling effect between the p-type and n-type topological surface states.