Exploiting Linear and Non linear Piezoelectricity in Novel Semiconductor Devices

When?

Thursday 3 May 2012, 13:00

Where?

02ATI02

Open to:

Staff, Students

Speaker:

Max Migliorato, School of Electrical and Electronic Engineering, University of Manchester

Piezotronics is a term coined in by 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 micropositioner devices but are also know to be present in GaN based light emitting diodes and lasers.[1] 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.[2] 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 non linear effects and discuss the possible applications to energy harvesting devices.

Biographical Notes:

Max Migliorato studied Physics at the University “La Sapienza” in Rome, Italy, specializing in Solid State Physics with a dissertation on Magneto-Optical Spectroscopy of Semiconductor Quantum Dots after spending a year at the University of Sheffield (UK). Following the successful defence of his dissertation, he obtained a scholarship from the UK Defence and Evaluation Research Agency to pursue research for a PhD in the Electronic and Electrical Engineering Department of the University of Sheffield, where he worked on Atomistic Simulations of Semiconductor Materials, linking those to the experimental activities in Electron Microscopy and Epitaxial Growth of nanostructures at the National Centre for III-V materials and devices. After being awarded his PhD in July 2003 he briefly worked in the same group as a Research Associate till May 2004 when he was awarded a Royal Academy of Engineering – EPSRC Research Fellowship. In February 2007 he was awarded an RCUK Fellowship, as a consequence of which he moved in to the School of Electrical and Electronic Engineering at the University of Manchester, where he has been since.

 

[1] S. Nakamura, G. Fasol, The Blue Laser Diode:  GaN Based Light Emitters and Lasers (Springer-Verlag, Berlin, 1997)

[1] M. A. Migliorato et al, Phys. Rev. B 74, 245332 (2006);  R. Garg et al, Appl. Phys. Lett. 95, 041912 (2009); J. Pal et al, Phys. Rev. B 84, 085211 (2011)