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

Abstract

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 cm2 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.

Multiple-Dimensionally Controllable Nucleation Sites of Two-Dimensional WS2/Bi2Se3 Heterojunctions Based on Vapor Growth

“…Both WS 2 and Bi 2 Se 3 demonstrate distinct crystal lattice stripes. The lattice constants of WS 2 and Bi 2 Se 3 are 0.27 and 0.21 nm, which perfectly agree with previous works. , Figure S5 shows selected area electron diffraction patterns of the WS 2 /Bi 2 Se 3 heterojunction. The area marked by red circle and blue circle shows diffractive spectra of WS 2 and Bi 2 Se 3 , suggesting that the two materials have hexagonal symmetrical diffraction spots.…”

“…Both WS 2 and Bi 2 Se 3 demonstrate distinct crystal lattice stripes. The lattice constants of WS 2 and Bi 2 Se 3 are 0.27 and 0.21 nm, which perfectly agree with previous works 37,45. FigureS5shows selected area electron diffraction patterns of the WS 2 /Bi 2 Se 3 heterojunction.…”

Nonlayered Two-Dimensional Defective Semiconductor γ-Ga2S3 toward Broadband Photodetection

“…Here, annealing has been employed to enhance electrode–2D material contacts and improve carrier mobility (Figure S11), and the obtained carrier mobility was about 1.06 cm 2 V –1 s –1 , which is comparable to the value of the devices based on ReS 2 and ReSe 2 flakes. , The relatively general value may be related to the internal vacancy defects in the crystal structure and the effect of adsorbates, and the low carrier mobility for the thinner flake may be due to its being more sensitive to external impurities scattering at the interface, compared with the thicker samples. Further improvement of the carrier mobility might be obtained by further optimizing film quality, , contact engineering, , and controlled doping. , The lower modulation ability of the thick samples may be due to charge screening, which causes free carriers to be gated only in the bottom layers, in accordance with the reported work . The uniformity of film quality has been proved by the electrical properties of 20 devices, which are based on samples from different substrates of the same synthesis process, and the obtained carrier mobilities are of the same order of magnitude (Figure S12).…”

Fast Fabrication of WS2/Bi2Se3 Heterostructures for High-Performance Photodetection

“…The thickness line profile implies a 1 nm thickness of WS 2 and an 8 nm thickness of Bi 2 Se 3 . With a theoretical thickness of a monolayer WS 2 of 0.7 nm and a monolayer Bi 2 Se 3 of 0.955 nm, this result confirms that our WS 2 flake is monolayer and the Bi 2 Se 3 flake is about 8-layers. , To confirm the interfacial coupling effect, room-temperature photoluminescence (PL) spectra and mapping were collected from the WS 2 /Bi 2 Se 3 heterostructure (Figure c,d). The results indicate that the WS 2 exhibits a strong PL emission peak at 2.01 eV (616 nm), which is comparable to a previously reported value of monolayer WS 2.…”