Single-Orientation Epitaxy of Quasi-1D Tellurium Nanowires on M-Plane Sapphire for Highly Uniform Polarization Sensitive Short-Wave Infrared Photodetection

Tellurium (Te), an elemental van der Waals semiconductor, has intriguing anisotropic physical properties owing to its inherent quais-1D crystal structure. Synthesizing ultrathin Te crystal with uniform orientation is important to its large-scale device applications, but that remains a great challenge. Herein, the nanoscale grooves-induced unidirectional epitaxy growth of 1D Te nanowires via physical vapor deposition on the annealed m-plane sapphire is demonstrated. By enhancing the annealing temperature from 1000 to 1300 degrees C, nanoscale grooves on m-plane sapphire arising along the [101 over bar $\overline 1 $0] direction and gradually distinct, and the corresponding Te nanowires grown on them turns from random to uniform, finally achieving nearly 95% unidirectional Te nanowires. The as-grown Te nanowires possess high crystallinity with clearly chiral helical chains along the c-axis direction and reveal thickness-tunable bandgap with prominent linear-dichroic. As results, the Te nanowire-based photodetectors demonstrate a broadband photoresponse from visible (532 nm) to short-wave infrared (2530 nm), with high responsivity of 327 A W-1 as well as strong and uniform polarization sensitivity (anisotropic ratio = 2.05) to 1550 nm light. The high crystallinity and superior anisotropy of Te nanowires, combined with the orientation-controlled preparation endows it with great feasibility for constructing chip-scale multifunctional optoelectronic devices.