Exploiting Linear and Non Linear Piezoelectricity in Novel Semiconductor Devices   
Dr. Geoffrey Tse
School of Electrical and Electronic Engineering，the University of Manchester, UK

October 9, 2012 11am-12pm,       205 G Hall


Piezotronics is a term coined in by Prof. Zhong Lin Wang (Georgia Institute of Technology, Atlanta, USA) and describes the exploitation of strain and deformation internal polarization fields in polar semiconductors.
Such fields already find applications in transducers and micropositioners devices but are also known to be present in GaN based light emitting diodes and lasers. Being a property of polar semiconductors it is present in both III-V and II-VI compounds, such as the technologically import ZnO.
For many years piezoelectricity was included in the design of devices only to first order. In recent years a great deal of evidence, both model and experimental data, has been generated that such effects need to be included to at least second order. The inclusion of such non linear effects produces surprising and non intuitive results, notably in zinc blende III-Vs the generation of fields of opposite polarity compared to the prediction of linear piezoelectricity.
In this presentation we will show the evidence for nonlinear effects and discuss the possible applications to energy harvesting devices.