Sun et al , J. Appl. Phys . 102 , 116101 (2009)

1. Coupling between Piezoelectricity and Charge Transport Property in ZnO NanowiresXudong Wang, University of Wisconsin-Madison, DMR 0905914 In order to understand the piezoelectric and semiconductor coupling effect in ZnO and eventually optimize the nanogenerator output and efficiency, it is critical to quantitatively predict geometry-related piezoelectric potential from a ZnO nanowire (NW). we have established a general theoretical framework for estimating the potential, output power and energy conversion efficiency of piezoelectric nanostructures. The piezoelectric property was studied in static and dynamic cases. Static analysis revealed the maximum piezoelectric potential that can be produced by a nanostructure when it is subjected to a constant external force and bent at a constant angle. Dynamic analysis is performed to study the power generation ability via the resonant vibration of these nanostructures agitated by ambient vibration energy. This theoretical framework was applied to different piezoelectric materials, including ZnO, BaTiO3, and PMN-PT. It revealed a comprehensive relationship between the mechanical energy harvesting ability and the nanomaterials’ morphologies, dimensions, and properties. O Ba Sr Si Top: The static analysis of the maximum allowable piezoelectric potential that can be generated by a ZnO NW at different lengthes. Inset is the corresponding full range plots of the piezoelectric potential to the force and size relationships. Left is the schematic structure and the coordinate system of a hexagonal ZnO NW Bottom: The output power and energy conversion efficiency of ZnO NWs at their resonant frequencies as functions of their length and side widths. Sun et al,J. Appl. Phys. 102, 116101 (2009)

2. ZnO Nanowire Growth Experiences for Wisc-AMP Undergraduate StudentsXudong Wang, University of Wisconsin-Madison, DMR 0905914 Through the collaboration with the Wisconsin alliance for minority participation (WiscAMP), we participated in the Academic Enrichment Program (AEP). The aim of this particular project is to increase awareness of science careers, scientific knowledge and science problem-solving skills of motivated underrepresented minority (URM) freshmen. We designed A series of ZnO nanowire synthesis and characterization experiments in our lab to educate the URM students with scientific background and perspectives of nanotechnology, and provide them with hands-on experience of nanomaterial synthesis. Undergraduate student from underrepresented minorities were learning how to grow ZnO nanowires .