Assessment of the vibrational resonant frequency of anisotropic black phosphorus nanoribbon

Abstract

Black phosphorus (BP) has been enjoying popularity in mechanical and optoelectronic devices due to its superior anisotropic puckered structure. However, the vibrational properties of BP remain unexplored which greatly limits its wide applications in resonance-based nano electromechanical system (NEMS) devices. Therefore, in order to design mechanically reliable ultra-sensitive nanosensors, molecular dynamics simulations are utilized to explore the vibrational properties of monolayer BP. We have systematically assessed the effects of the initial actuation amplitude, internal vacancy density and mechanical strain on the vibrational properties of monolayer BP along the armchair and zigzag directions. It is found that the pristine monolayer BP exhibits lower energy disspation and smaller dominant resonant frequency during free vibration along the armchair direction than along the zigzag direction, indicating the anisotropic mechanical vibrational properties of monolayer BP, which further result in anisotropic multimode resonant characteristics in the vibration frequency spectrum. Additionally, the dominant frequency monotonically decreases gradually with increment of the internal vacancy density, while increasing with increment of the initial actuation amplitude and the mechanical strain. The energy dissipation increases gradually with increment of the initial actuation amplitude and internal vacancy density, but decreases under mechanical strain. Overall, these findings provide a fundamental understanding of the resonant properties of monolayer anisotropic BP that sheds light on its applications in micro- or nano-resonator-based devices.