One-dimensional Semiconducting and Piezoelectric Oxide Nanostructures - Synthesis, growth mechanisms and potential applications

Zhong Lin Wang
Georgia Institute of Technology

Quasi-one-dimensional (1D) nanostructures (nanowires, nanobelts and nanorods) are the forefront nanomateirals for nanotechnology. Oxide nanostructures have been synthesized for a wide range of semiconducting oxides [1] that are potential building blocks for constructing numerous nanodevices. Using the technique demonstrated for measuring the mechanical properties of nanotubes [2,3], the mechanical and field emission properties of the oxide nanobelts have been characterized. Field effect transistors [4], ultra-sensitive nano-size gas sensors [5], nanoresonators and nanocantilevers [6] have been fabricated using nanobelts.

Among all of the oxide nanostructures we have investigated, ZnO is very unusual. The two important characteristics of the wurtzite structured ZnO are the non-central symmetry and the polar surfaces. The structure of ZnO can be described as a number of alternating planes composed of tetrahedrally coordinated O2- and Zn2+ ions, stacked alternatively along the c-axis. The oppositely charged ions produce positively charged (0001)-Zn and negatively charged (000-1)-O polar surfaces, resulting in a normal dipole moment and spontaneous polarization along the c-axis. The polar surfaces give raise a few interesting growth features, such as the formations of nanosprings [7], nanorings [8], nanobows [9] and nanohelices [10]. These nanostructure are semiconductive and piezoelectric and have potential applications as nano-scale sensors, traducers, and actuators. This presentation will be about the synthesis, characterization and potential applications of these novel nanostructures [11].

[1] Z.W. Pan, Z.R. Dai and Z.L. Wang, Science, 209 (2001) 1947.

[2] P. Poncharal, Z.L. Wang, D. Ugarte and W.A. de Heer, Science, 283 (1999) 1513.

[3] R.P. Gao, Z.L. Wang, Z.G. Bai, W. de Heer, L. Dai and M. Gao, Phys. Rev. Letts., 85 (2000) 622.

[4] M. Arnold, P. Avouris, Z.L. Wang,. Phys. Chem. B, 107 (2002) 659.

[5] E. Comini, G. Faglia, G. Sberveglieri, Zhengwei Pan, Z. L. Wang Applied Physics Letters, 81 (2002) 1869.

[6] W. Hughes and Z.L. Wang, Appl. Phys. Letts., 82 (2003) 2886.

[7] X.Y. Kong and Z.L. Wang, Nano Letters, 2 (2003) 1625 + cover.

[8] X.Y. Kong, Y. Ding, R.S. Yang, Z.L. Wang, Science, 303 (2004) 1348.

[9] W.L. Hughes and Z.L. Wang, J. Am. Chem. Soc., 126 (2004) 670

[10] P.X. Gao, Y. Ding, W.J. Mai, W.L. Hughes, C.S. Lao and Z.L. Wang, Science, 309 (2005) 1700.

[11] Thanks the support from NSF, DARPA, NASA and Airforce.

[12] for details see:

Dr. Wang is a Regents' Professor and Director, Center for Nanostructure Characterization and Fabrication, Georgia Tech. He has authored and co-authored four scientific reference and textbooks and over 400 journal articles, 40 review papers and book chapters, edited and co-edited ten volumes of books on nanotechnology, and held 8 patents and provisional patents. Dr. Wang is the world’s top 25 most cited authors in nanotechnology from 1992-2002. His publications have been cited over 10,000 times. He has been elected to the European Academy of Science in 2002, fellow of APS, has received the 2001 S.T. Li prize for Outstanding Contribution in Nanoscience and Nanotechnology, the 2000 and 2005 Georgia Tech Faculty Research Award, the 1999 Burton Medal from Microscopy Society of America, 1998 US NSF CAREER award, and 1998 China-NSF Oversea Outstanding Young Scientists Award. He is a member of the editorial board of over 10 journals. His most recent research focuses on oxide nanobelts and nanowires, in-situ techniques for nano-scale measurements, self-assembly nanostructures, fabrication of nano devices, and properties of magnetic nanostructures.