Fast time response from Si–SiGe undulating layer superlattices

Response of Bose gases in time-dependent optical superlattices

The dynamic response of ultracold Bose gases in one-dimensional optical lattices and superlattices is investigated based on an exact numerical time evolution in the framework of the Bose-Hubbard model. The system is excited by a temporal amplitude modulation of the lattice potential, as it was already realized in experiment. For regular lattice potentials, the dynamic signatures of the superflu...

VALENCE BAND STRUCTURE OF STRAINED-LAYER Si-Si0.5Ge0.5 SUPERLATTICES

We calculate the valence subband dispersion of Sio,5Ge,,5 Si strained layer structures grown on a Si (001) substrate and on a Si0,,5Ge0,25 buffer. We use the 6x6 Luttinger-Kohn Hamiltonian, including the effects both of strain and of the split-off band. The heavy-hole zone centre states are separated by over 60meV from the light-hole states and the highest valence subband has a low zone-centre ...

Wannier-based definition of layer polarizations in perovskite superlattices.

In insulators, the method of Marzari and Vanderbilt [Phys. Rev. B 56, 12 847 (1997)] can be used to generate maximally localized Wannier functions whose centers are related to the electronic polarization. In the case of layered insulators, this approach can be adapted to provide a natural definition of the local polarization associated with each layer, based on the locations of the nuclear char...

Structural characterization of Si,Ge, strained layer superlattices

Si,Ge, strained layer superlattice (SLS) structures were grown by molecular beam epitaxy on Ge$ii --x buffer layers on (100) Si substrates to determine the effects of buffer layer composition, SLS thickness ratio, and superlattice periodicity, on the overall quality of these structures. X-ray diffraction methods were used to determine how closely actual periodicities and compositions met target...

Electronic structure of strained-layer AlAs/InAs (001) superlattices.