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

TLDR

Infrared detection at optical communication wavelengths is critical for commercial and military applications, and layered Bi₂Se₃, with a 0.3 eV bandgap, is a promising candidate, though large‑size ultrathin flake synthesis remains challenging. The study seeks to synthesize large‑size, ultrathin Bi₂Se₃ flakes with high crystal quality to enable infrared photodetectors. Large‑size (0.2–0.4 mm) and ultrathin (3 nm–few nm) 2D Bi₂Se₃ flakes were obtained by suppressing nucleation density. The resulting Bi₂Se₃ photodetector achieved an on/off ratio of 972.5, responsivity of 23.8 A W⁻¹, external quantum efficiency of 2035 %, and a back‑gate transistor exhibited a 10⁶ on/off ratio and 39.4 cm² V⁻¹ s⁻¹ mobility, demonstrating high performance at 1456 nm.

Abstract

Abstract Infrared detection at optical communication wavelength is of great significance because of their diverse commercial and military communication applications. The layered Bi 2 Se 3 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 Bi 2 Se 3 flakes remains a challenge owing to complex nucleation process and infrared telecommunication photodetectors based on Bi 2 Se 3 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 Bi 2 Se 3 flakes with high crystal quality are obtained by suppressing the nucleation density. More importantly, back‐gate field‐effect transistor based on Bi 2 Se 3 flake exhibits an ultrahigh on/off current ratio of 10 6 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 Bi 2 Se 3 ‐based photodetector at 1456 nm in the E‐band of the telecommunication range. With controlled morphology and excellent photoresponse performance, the Bi 2 Se 3 photodetector shows great potential in the optoelectronic field including communications, military, and remote sensing.