Title:  Piezoelectric Thin Films and Nanowires: Synthesis and Characterization

Abstract: Traditional vapor phase deposition techniques of PZT offer poor conformality over three-dimensional surfaces due to their reactant transport mechanisms. As an alternative, sol-gel synthesis may provide new process possibilities to overcome this hurdle but the film quality is usually inferior. The first part of this study is dedicated to the characterization of the electric properties and yield of PZT thin film prepared by the sol-gel process. Several conducting materials that can be coated on three-dimensional surfaces have been evaluated as electrodes, and the possibility to form a conformal coating over a three-dimensional surface by solution coating techniques has been demonstrated.

ZnO and GaN micro/nanowires are promising piezoelectric materials for energy harvesting and piezotronic device applications.  The second part of this study is focused on ZnO and GaN micro/nanowires grown by physical vapor deposition techniques. The morphology and chemical compositions are revealed by electron microscopy. Utilizing the as-grown ZnO nanowires, single nanowire based photocell is fabricated, and its performance is studied in terms of its response time, repeatability, excitation position and polarization dependence upon He-Cd UV-laser illumination. Employing the as-grown GaN nanowires, single nanowire based strain sensor is demonstrated, and its behavior is discussed in terms of the polar axis orientation of the nanowire and the Schottky contacts.