Novel approach to tuning the physical properties of organic-inorganic hybrid semiconductors

We discuss theoretically a novel approach to tailoring the properties of a new family of organic-inorganic hybrid superlattices, using two isostructural materials, ZnSe(en)0.5 and ZnTe(en)0.5, as examples. Replacing Se with Te leads to a number of nontrivial changes: the conduction band parity, singularity type, conductivity in the superlattice direction, and the p-type dopability. Experimentally, we report the first unambiguous observation of exciton-polariton emission in a hybrid semiconductor, i.e., ZnTe(en)0.5 . The band-edge excitonic transitions in both emission and absorption are explained by the calculated electronic structures.     

Total negative refraction in real crystals for ballistic electrons and light

It is found that there exists a category of material interfaces, readily available, that not only can provide total refraction (i.e., zero reflection) but can also give rise to amphoteric refraction (i.e., both positive and negative refraction) for electromagnetic waves in any frequency domain as well as for ballistic electron waves. These two unusual phenomena are demonstrated experimentally for the propagation of light through such an interface.     

Eigenstate localization in an asymmetric coupled quantum well pair

Optical pumping of a type-I/type-II coupled asymmetric quantum well pair induces a spatially separated two dimensional charge carriers plasma in the well’s wide and narrow parts. Treating the two coupled wells as a single system we find that the eigenstate probability distribution localizes exclusively either in the wide or the narrow parts of the well pair. The energy of the narrow-well localized state determines the minimal excitation energy for optically pumped charge carriers separation. In a previously used design [Guliamov et al., PRB 64 035314 (2001)] this narrow well transition energy was measured to correspond to a wavelength of 646 nm. We propose modifications to the design suggested earlier with the purpose of pushing up the energy required for the optical pumping of the two-dimensional plasma into the green and blue regions of the visible spectrum.     

Giant spin-orbit bowing in GaAs1-xBix

We report a giant bowing of the spin-orbit splitting energy Delta0 in the dilute GaAs1-xBix alloy for Bi concentrations ranging from 0% to 1.8%. This is the first observation of a large relativistic correction to the host electronic band structure induced by just a few percent of isoelectronic doping in a semiconductor material. It opens up the possibility of tailoring the spin-orbit splitting in semiconductors for spintronic applications.