Molybdenum Disulfide Nanoribbons with Enhanced Edge Nonlinear Response and Photoresponsivity.

MoS nanoribbons have attracted an increased interest due to their properties, which can be tailored by tuning their dimensions. Herein, we demonstrate the growth of MoS nanoribbons and 3D triangular crystals formed by the reaction between ultra-thin films of MoO grown by Pulsed Laser Deposition and NaF in a sulfur-rich environment. The multilayer nanoribbons can reach up to 10 μm in length, and feature single-layer edges, forming a monolayer-multilayer MoS junction enabled by the lateral modulation in thickness. The single-layer edges of the nanoribbons show a pronounced second harmonic generation due to the symmetry breaking, in contrast to the centrosymmetric multilayer structure, which is unsusceptible to the second-order nonlinear process. A pronounced splitting of the Raman spectra was observed in MoS nanoribbons arising from distinct contributions from the monolayer edges and multilayer core. Nanoscale imaging reveals a blue-shifted exciton emission of the monolayer edge compared to the triangular MoS monolayers due to built-in local strain and disorder. We further report on an ultrasensitive photodetector made of a single MoS nanoribbon with a responsivity of 8.72×10 A/W at 532 nm, among the highest reported up-to-date for single-nanoribbon photodetectors. Our findings can inspire the design of MoS semiconductors with tunable geometries for efficient optoelectronic devices. This article is protected by copyright. All rights reserved.