Center for Functional Nanomaterials Seminar

"Can We Apply the Notions of Band-offset, Potential Well and Barrier to Nanoscale Heterostructures?"

Presented by Christoph Delerue, Centre National de la Recherche Scientifique, Lille, France

Thursday, October 13, 2011, 11:00 am — Bldg. 735 - Conf Rm B

Epitaxially-grown semiconductor heterostructures give the possibility to tailor the potential landscape for the carriers in a very controlled way. In planar lattice-matched heterostructures, the potential has indeed a very simple and easily predictable behavior: it is constant everywhere except at the interfaces where there is a step (discontinuity) which only depends on the composition of the semiconductors in contact. In this presentation, we show that this universally accepted picture can be invalid in nanoscale heterostructures (e.g., quantum dots, rods, nanowires) which can be presently fabricated in a large variety of forms. Self-consistent tight-binding calculations applied to systems containing up to 75000 atoms indeed demonstrate that the potential may have a more complex behavior in axial hetero-nanostructures: The band edges can show significant variations far from the interfaces if the nanostructures are not capped with a homogeneous shell. These results suggest new strategies to engineer the electronic properties of nanoscale objects, e.g. for sensors and photovoltaics.

Y.M. Niquet and C. Delerue, Phys. Rev. B 84, 075478 (2011).

Hosted by: Mark Hybertsen

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