Orientation-Dependent Electronic and Mechanical Properties of Tungsten Nitride Nanosheets: Implications for Flexible Devices

Transition metal nitrides play an essential role in various technological applications due to their superior mechanical properties and high chemical stability. The synthesis and characterization of WN nanosheets further affirmed the role of transition metal nitrides as coatings that enable materials to be mechanically robust. In this paper, we report the results of a theoretical study based on density functional theory and molecular dynamics simulations focusing on the surface orientation and termination-dependent structural, electronic, and mechanical properties of WN nanosheets. The results suggest that the W-terminated (0001) nanosheet is energetically preferable and easily grown on a substrate. Moreover, the metallic nature is robust in the designed nanosheets regardless of the growth direction or surface termination. A relatively high mechanical strength is predicted for W-terminated and non-polar nanosheets, whereas N-terminated nanosheets exhibit fracture strain values comparable to graphene and BN monolayers. The results demonstrate that the mechanical strength of these nanosheets can be tuned by the growth directions and terminations, which suggests that they can be promising candidates for designing mechanically strong and flexible devices.