In-plane Epitaxy of Bi2S3Nanowire Arrays for Ultrasensitive NIR Photodetectors

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 Bi2S3NW arrays on mica with a large lattice mismatch. The orthorhombic Bi(2)S(3)NWs grow epitaxially with the axial direction of⟨001⟩Bi2S3along the six symmetric directions of the mica. Transmission electron microscope measurements show that the epitaxial relationships are[001]Bi2S3||[100]micaand[32 over bar 0]Bi2S3||[010]micaalong 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 x 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.