Since this is my area of expertise, let me give you the bad news.

Although metallic - insulating - superconducting superlattices have been explored for a good long while now, none of these fabrications have definitively yielded any demonstrable and repeatable or remarkable increases in Tc, or in the case of thermoelectrics - zTs. This area of research is in its infancy. Any superlattice effects are expected to be 'weak', as in this result, and obtain only modest enhancement of the field dependent properties under study. These investigations are more applicable to research, than industrial scale applications, at least yet.

On the other hand, an basic science the understanding of the mechanisms of superconductivity and thermoelectricity (or any other interesting combinations of field dependent observables and properties derivable from the Onsagar approach to these matters) has made very great strides in the last few weeks and months. Quantum criticality as a mechanism of enhancement of the fundamental physical properties of materials will remain a general approach to progress in this field, and electronic superlattice fabrication will remain a single approach to success.

This is generally in line with my previous post of the benefits of free electron and other advanced spectroscopic and fabrication techniques within the domain of nanotechnology, as a field within condensed matter physics.

If you want a 'breakthrough', you only have to look as early as last night :

http://arxiv.org/abs/0810.2823

Discrete Properties of Intrinsic Localized Modes Observed in the High Temperature Vibrational Spectrum of NaI

Inelastic neutron measurements of the high temperature lattice excitations in NaI show surprising features. In thermal equilibrium at 555 K an intrinsic mode, localized in three dimensions, is observed at a single frequency near the center of the spectral phonon gap, polarized along [111]. At higher temperatures mixing between the intrinsic localized mode and the zone boundary TO mode is observed. Higher energy inelastic neutron and x-ray scattering measurements on a room temperature NaI crystal indicate that the creation energy of the ground state of the intrinsic localized mode is 299 meV.

http://www.lassp.cornell.edu/~sievers/ilm/igm3d/index.html

Check out the 3D Java crystal. Click and drag it.

This is big. Trust me.