| AVS 63rd International Symposium & Exhibition | |
| 2D Materials Focus Topic | Friday Sessions |
| Session 2D+NS-FrM |
| Session: | 2D Materials: Device Physics and Applications |
| Presenter: | Zenghui Wang, Case Western Reserve University |
| Authors: | Z. Wang, Case Western Reserve University H. Jia, Case Western Reserve University P.X.-L. Feng, Case Western Reserve University |
| Correspondent: | Click to Email |
Black phosphorus (P) has emerged as a layered semiconductor with unique crystal structure featuring corrugated atomic layers and strong in-plane anisotropy in its physical properties. In particular, it is predicted to exhibit strong in-plane mechanical anisotropy, which shall lead to previously inaccessible dynamic responses in resonant 2D nanostructures [1], and new opportunities for studying carrier-lattice interaction in atomic layers. It is therefore of both practical and fundamental importance to systematically investigate the mechanical anisotropy in black P crystal and NEMS devices.
Enabled by the first demonstration of black P resonant nanostructures [2] with multimode responses, we show that the spatial mapping of the multimode resonance mode shapes [3] creates a new means for precise determination of black P crystal orientation (i.e., the anisotropic zigzag and armchair axes) [4] . Further, the multimode technique enables simultaneous quantification of the anisotropic mechanical properties (i.e., elastic moduli along both major crystal axes): combined with finite element method (FEM) modeling, we determine the Young’s moduli of multilayer black P to be 116.1 GPa and 46.5 GPa in zigzag and armchair directions, respectively. In addition, we demonstrate that electrostatic gating induced straining can continuously tune the mechanical anisotropic effects on multimode resonances in black P electromechanical devices. Our results show that multimode resonant response manifests the unique mechanical anisotropy effect in black P nanodevices, and provides a new method for determine the material’s crystal orientation and elastic properties in situ, independent from conventional optical, electrical, and nanoindentation calibration techniques.
[1] Wang, Z. & Feng, P. X.-L. Design of Black Phosphorus 2D Nanomechanical Resonators by Exploiting the Intrinsic Mechanical Anisotropy. 2D Materials 2, 021001 (2015).
[2] Wang, Z., Jia, H., Zheng, X.-Q., Yang, R., Wang, Z., Ye, G.J., Chen, X.H., Shan, J., & Feng, P. X.-L. Black Phosphorus Nanoelectromechanical Resonators Vibrating at Very High Frequencies. Nanoscale. 7, 877 (2015).
[3] Wang, Z., Lee, J., & Feng, P. X.-L. Spatial Mapping of Multimode Brownian Motions in High Frequency Silicon Carbide (SiC) Microdisk Resonators. Nature Communications 5, 5158 (2014).
[4] Wang, Z., Jia, H., Zheng, X.-Q., Yang, R., Ye, G.J., Chen, X.H., & Feng, P. X.-L. Resolving and Tuning Mechanical Anisotropy in Black Phosphorus via Nanomechanical Multimode Resonance Spectromicroscopy. under review. (2016).