In‐plane Epitaxy of Bi₂S₃ Nanowire Arrays for Ultrasensitive NIR Photodetectors

Abstract

The direct growth of semiconductor nanowire (NW) arrays horizontally aligned on a substrate is critically important for the applications of NWs in electronic or optoelectronic devices at the circuit level. The strict requirement of lattice matching between a substrate and a material in the covalent epitaxy of crystals makes the wire arrays be grown on the substrates only with similar lattice parameters. Herein, a van der Waals epitaxy route is developed to realize the in‐plane growth of large‐scale Bi 2 S 3 NW arrays on mica with a large lattice mismatch. The orthorhombic Bi 2 S 3 NWs grow epitaxially with the axial direction of along the six symmetric directions of the mica. Transmission electron microscope measurements show that the epitaxial relationships are and along the length and width directions of the wires, respectively. More importantly, photodetectors based on Bi 2 S 3 NWs show a wide photoresponse spectrum range from 500 to 980 nm. A high responsivity (5233 A W −1 ) and a specific detectivity (1.8 × 10 12 Jones) are achieved under 830 nm light irradiation with ultralow intensity (64 nW cm −2 ). In addition, the photodetectors exhibit high stability with at least 48 day storage in ambient atmosphere or with 1000 times bending.