ORC Seminar Series

Speaker: Professor Volkmar Dierolf

Date: 18 March

Time: 2pm

Venue: B46 LT C (2005)

Abstract

This talk will include a brief introduction into Raman spectroscopy and optical spectroscopy of rare earth ions and how the obtained information can be used to determine the internal sub-micron scale properties of materials. The power of this experimental approach will be demonstrated for two material systems:

(1) LiNbO3 and (2) GaN.

For LiNbO3 it will be shown that the dynamics of the ferroelectric domain walls and their motions can be imaged with both Raman spectroscopy as well as the emission of Erbium ions. It will be shown that the presence of ferroelectric domain walls unexpectedly can be felt on several length scales ranging from the nm-scale to almost 100 µm.

For rare earth doped GaN, which has been considered for electroluminescence and spintronics devices, a strong incorporation site dependence of the excitation mechanism of the rare earth ions will be demonstrated

Biography

Dr. Dierolf is a Professor of Physics and Materials Science and Engineering at Lehigh University in Bethlehem, PA, USA where he started in the year 2000. His research is focused on optical spectroscopy and microscopy of defects in insulating materials and semiconductors. He has published several books and book chapter along with 100+ reviewed articles including several invited review articles.

He is leading the wide bandgap semi-conductor activities within the Center for Optical Technologies at Lehigh University and is the lead Investigator of a NSF-DFG Materials World Network Grant dealing with the Nanoscale structure and shaping of ferroelectric domains. This collaboration consists of groups at Penn State University, University of Florida, Lehigh University, University of Bonn, and University of Paderborn.

He is currently a Mercator Visiting Professor at the University of Bonn.

In 1992, he received his Ph.D from the University of Utah working on molecular defects in alkali halides. In 2000, he received a Habilitation from the University of Paderborn and holds since then private lectureship in Paderborn. 

He is currently a principal editor of Journal of Materials Research and the President of the Tri-State Chapter of the OSA.