Piezoelectric properties of zinc oxide nanowires: an ab initio study

• Published in: Nanotechnology 2013-11, Vol.24 (47), p.475401-5
• Main Authors: Korir, K K, Cicero, G, Catellani, A
• Format: Article
• Language: English
• Subjects: Applied sciences; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Crystal structure; Deformation mechanisms; Delay; Electron states; Electronics; Exact sciences and technology; Materials science; Mathematical analysis; Methods of electronic structure calculations; Molecular electronics, nanoelectronics; Nanocrystalline materials; Nanoscale materials and structures: fabrication and characterization; Nanostructure; Nanowires; Physics; Piezoelectricity; Quantum wires; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Zinc oxide
• ISSN: 0957-4484; 1361-6528
• DOI: 10.1088/0957-4484/24/47/475401

Nanowires made of materials with non-centrosymmetric crystal structures are expected to be ideal building blocks for self-powered nanodevices due to their piezoelectric properties, yet a controversial explanation of the effective operational mechanisms and size effects still delays their real exploitation. To solve this controversy, we propose a methodology based on DFT calculations of the response of nanostructures to external deformations that allows us to distinguish between the different (bulk and surface) contributions: we apply this scheme to evaluate the piezoelectric properties of ZnO [0001] nanowires, with a diameter up to 2.3 nm. Our results reveal that, while surface and confinement effects are negligible, effective strain energies, and thus the nanowire mechanical response, are dependent on size. Our unified approach allows for a proper definition of piezoelectric coefficients for nanostructures, and explains in a rigorous way the reason why nanowires are found to be more sensitive to mechanical deformation than the corresponding bulk material.