Design of Black Phosphorus 2D Nanomechanical Resonators by Exploiting the Intrinsic Mechanical Anisotropy

TL;DR

This paper explores the design of black phosphorus 2D nanomechanical resonators by leveraging its intrinsic mechanical anisotropy, revealing unique multimode resonant behaviors and orientation-dependent responses for advanced device applications.

Contribution

It provides a combined analytical and numerical framework to understand and utilize black phosphorus's anisotropic mechanical properties in nanomechanical resonator design.

Findings

Thicker black P devices show pronounced anisotropic resonant signatures.

Anisotropy leads to unique multimode resonant characteristics.

Device geometry and crystal orientation significantly influence resonant responses.

Abstract

Black phosphorus (P), a layered material that can be isolated down to individual 2D crystalline sheets, exhibits highly anisotropic mechanical properties due to its corrugated crystal structure in each atomic layer, which are intriguing for 2D nanomechanical devices. Here we lay the framework for describing the mechanical resonant responses in free-standing black P structures, by using a combination of analytical modeling and numerical simulation. We find that thicker devices (>100nm) operating in the elastic plate regime exhibit pronounced signatures of mechanical anisotropy, and can lead to new multimode resonant characteristics in terms of mode sequences, shapes, and orientational preferences that are unavailable in nanomechanical resonators made of isotropic materials. In addition, through investigating devices with different geometries, we identify the resonant response's dependence on crystal orientation in asymmetric devices, and evaluate the effects from the degree of anisotropy. The results suggest a pathway towards harnessing the mechanical anisotropy in black P for building novel 2D nanomechanical devices and resonant transducers with engineerable multimode functions.