Submillimeter 2D Bi2Se3 Flakes toward High-Performance Infrared Photodetection at Optical Communication Wavelength

Infrared detection at optical communication wavelength is of great significance because of their diverse commercial and military communication applications. The layered Bi2Se3 with a narrow band gap of 0.3 eV is regarded as a promising candidate toward high-performance terahertz to infrared applications. However, the controllable synthesis of large-size ultrathin Bi2Se3 flakes remains a challenge owing to complex nucleation process and infrared telecommunication photodetectors based on Bi2Se3 flakes are rarely reported. Here, large size (submillimeter: 0.2-0.4 mm in lateral dimensions) and ultrathin (thickness: 3 nm to few nanometers) 2D Bi2Se3 flakes with high crystal quality are obtained by suppressing the nucleation density. More importantly, back-gate field-effect transistor based on Bi2Se3 flake exhibits an ultrahigh on/off current ratio of 106 and competitive mobility of 39.4 cm(2) V-1 s(-1). Moreover, excellent on/off ratio of 972.5, responsivity of 23.8 A W-1, and external quantum efficiency of 2035% are obtained from Bi2Se3-based photodetector at 1456 nm in the E-band of the telecommunication range. With controlled morphology and excellent photoresponse performance, the Bi2Se3 photodetector shows great potential in the optoelectronic field including communications, military, and remote sensing.