An experimental and theoretical study on nanomachining forces along zigzag and armchair lattice orientations of monolayer MoS2

Abstract

Recent progresses in the synthesis of large-area and stable atomically thin MoS2 have evoked enormous interest toward the future applications of two-dimensional (2D) electronics. Although considerable theoretical researches have been conducted to examine the zigzag and armchair lattice orientations of MoS2, which are closely related to the physical and chemical properties of this material, experimental investigations into these two orientations are still quite rare. In this paper, we present an experimental study on nanofabrication along the zigzag and armchair orientations of monolayer MoS2 using normal- and phase-mode AFM. After identifying the zigzag and armchair orientations, distinctly different nanofabrication forces along these two orientations are obtained, which are approximately 15.9 nN and 35.8 nN, respectively. To determine the underlying mechanism of this discrepancy, molecular dynamics simulation is performed. The simulated nanofabrication forces along the zigzag and armchair orientations are 12.16 ± 0.59 nN and 21.45 ± 0.74 nN, respectively, in good agreement with the experimentally measured ones. The results provide a better understanding of the zigzag and armchair lattice orientations of monolayer MoS2 as well as a promising approach to closed-loop fabrication of 2D materials with desirable lattice orientations.