Computational Modelling Group

Seminar  10th February 2010 1 p.m.  Lecture Room A, Lanchester Building (7/3009)

SYMBIOSIS Seminar - Iris Nandhakumar - Metamaterials with a twist

Iris Nandhakumar

Materials, Micromagnetics, Superconductivity
Thomas Blumensath

Metamaterials with a twist

Nanostructuring of semiconductors and metals is now a clear route to optimise and elicit new functional properties, e.g. allowing quantum engineering of electron and photon states. Hence materials with mesoporous nanoarchitectures (2–50 nm) exhibit enhanced electronic, optical and magnetic properties in comparison to their non-mesoporous counterparts. Recently we have devised an elegant and highly versatile route to the production of a wide range of nanostructured materials with well-defined mesoporous architectures of extended spatial periodicities. This method utilises lyotropic liquid crystalline (LC) mesophases of non-ionic surfactants as templates for electrochemical growth. Here we report the fabrication of adherent nanostructured semiconductor films such as selenium, tellurium and cadmium telluride that have been fabricated by this method. Such materials would be of considerable fundamental interest because they are entirely composed of surface atoms (no atom in the structure is further than 1.5 nm from a surface). As a consequence we expect that these materials should exhibit unusual charge carrier dynamics, improved collection of the photogenerated carriers and hence solar conversion efficiencies. Nanostructured semiconductors will show quantum size effects by virtue of their reduced dimensionality and nanometre lengthscales (from 2 to 15nm). The ability to electrodeposit mesoporous nanostructured semiconductors highlights the possibility of creating a new class of materials that would exhibit unusual electronic and optical properties.