Electronic coupling between Wannier and Frenkel excitons in an inorganic/organic semiconductor hybrid structure is experimentally observed. Time-resolved photoluminescence and excitation spectroscopy directly demonstrate that electronic excitation energy can be transferred with an efficiency of up to 50% from an inorganic ZnO quantum well to an organic [2,2-p-phenylenebis-(5-phenyloxazol), alpha-sexithiophene] overlayer. The coupling is mediated via dipole-dipole-interaction analog to the Förster transfer in donor-acceptor systems.

Control over the electronic structure of organic/inorganic semiconductor interfaces is required to realize hybrid structures with tailored opto-electronic properties. An approach towards this goal is demonstrated for a layered hybrid system composed of p-sexiphenyl (6P) and ZnO. The molecular orientation can be switched from "upright-standing" to "flat-lying" by tuning the molecule-substrate interactions through aggregation on different crystal faces. The morphology change has profound consequences on the offsets between the molecular frontier energy levels and the semiconductor band edges. The combination of ZnO surface dipole modification through molecule adsorption and the orientation-dependence of the ionization energy of molecular layers shift these offsets by 0.7 eV. The implications for optimizing hybrid structures with regard to exciton and charge transfer are discussed.

Single-phase ZnCdO alloys with a band gap extending from the violet to yellow spectral range are fabricated by molecular beam epitaxy using extremely low growth temperatures in conjunction with O-rich growth conditions. The Cd concentration can be systematically adjusted via the Cd∕Zn beam pressure ratio. Despite growth temperatures as low as 150°C, layer-by-layer growth is accomplished allowing for the preparation of ZnCdO∕ZnO quantum well structures. Both epilayers and quantum wells exhibit strong band-gap-related emission at room temperature in the whole composition range.

We report on the strong coupling of surface plasmon polaritons and molecular vibrations in an organic-inorganic plasmonic hybrid structure consisting of a ketone-based polymer deposited on top of a silver layer. Attenuated-total-reflection spectra of the hybrid reveal an anticrossing in the dispersion relation in the vicinity of the carbonyl stretch vibration of the polymer with an energy splitting of the upper and lower polariton branch up to 15 meV. The splitting is found to depend on the molecular layer thickness and saturates for micrometer-thick films. This new hybrid state holds a strong potential for application in chemistry and optoelectronics.

We report on a specific growth procedure combining low-temperature growth of ZnMgO and postgrowth annealing at intermediate temperatures. Despite the large lattice misfit induced by the sapphire substrate, layer-by-layer growth is accomplished up to the phase-separation limit found at a c-lattice constant of 0.5136nm and Mg mole fraction of 0.40. The procedure allows us to grow quantum wells with atomically smooth interfaces in a wide range of structural designs exhibiting prominent emission features up to room temperature.