Structural Flexibility and Alloying in Ultrathin Transition-Metal Chalcogenide Nanowires.

Metallic transition-metal chalcogenide (TMC) nanowires are an important building block for 2D electronics that may be fabricated within semiconducting transition-metal dichalcogenide (TMDC) monolayers. Tuning the geometric structure and electronic properties of such nanowires is a promising way to pattern diverse functional channels for wiring multiple units inside a 2D electronic circuit. However, few experimental investigations have been reported exploring the structural and compositional tunability of these nanowires, due to difficulties in manipulating the structure and chemical composition of an individual nanowire. Here, using a combination of scanning transmission electron microscopy (STEM) and density functional theory (DFT), we report that TMC nanowires have substantial intrinsic structural flexibility and their chemical composition can be manipulated. Rotational twisting, axial kinking, and branching of an individual nanowire is consistently observed and junctions with well-ordered atomic structures can be fabricated. We also show that the density of states of these nanowires can be finely tuned via alloying either the chalcogen or the transition-metal elements, where the chalcogen alloying can be further controlled by the acceleration voltage of the electron beam during the fabrication. The results open up the possibility of tailoring the properties of TMC nanowires, paving the way for robust ultrasmall interconnects in TMDC-based 2D flexible nanoelectronics.