Title: III-V Nanostructures grown by Molecular Beam Epitaxy (MBE) and Research in the Fontcuberta Research Group at EPFL

Speaker: Gözde TUTUNCUOĞLU - École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland

Date:Time: Wednesday, 18. November, 2015 at 12:40

Place: FENS G032

Abstract: III-V nanostructures are of great interest since their intrinsic properties like direct band gap, high electron/hole mobility or spin-orbit interaction can open up wide range of applications in high speed electronics, optoelectronics, photovoltaics etc. The understanding of the growth mechanism of such III-V nanostructures would enable us to tailor their properties for novel optoelectronic applications.

In this talk, we present our results on III-V NWs and nanomembranes grown by Molecular Beam Epitaxy (MBE). The talk will start with the introduction of the growth mechanisms of selfcatalyzed GaAs NWs and selective area epitaxy (SAE) GaAs nanomembranes and continue with the designed heterostructures based on them. It has been already shown for GaAs/AlGaAs core/shell NWs that the high degree of precision over the growth conditions offered by MBE and the lattice match of GaAs and AlGaAs enable us to obtain high quality heterostructures and such structures demonstrate unique optical properties. [1][2] In addition to our work on GaAs/AlGaAs core/shell nanowires we have expanded to other geometries, GaAs membranes. GaAs nanomembranes have the potential to be defect-free when they are grown in a particular orientation, while twin defects, stacking faults and polytypism are more likely to occur in the case of NWs. [3] Our ultimate purpose is to understand the effect of geometry and crystal structures of mentioned nanostructures on their optoelectronic properties.

References:

[1]Anna Fontcuberta i Morral et al. Small 4 (7): 899–903. (2008)

[2]M. Heiss et al. Nature Materials 12, 439–444 (2013)

[3]G. Tutuncuoglu et al. Nanoscale (2015)

BIO: Gozde Tutuncuoglu did her bachelor’s studiesp in Sabanci University, Materials Science and Engineering Program with a minor in Physics. During her studies she did an internship in Ludwig Maximilian University Munich in the scope of Nanosystems Initiative Munich program and then continued her studies in Switzerland, Ecole Polytechnique Federal de Lausanne. Currently she is in the last year of her PhD during which she has been working on “Optoelectronic Properties of III-V Nanostructures grown by Molecular Beam Epitaxy.”

Contact: Cleva Ow Yang