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HL: Fachverband Halbleiterphysik

HL 32: Focussed Session: Inorganic/Organic Semiconductor Hybrid Structures I

HL 32.2: Hauptvortrag

Dienstag, 15. März 2011, 10:45–11:15, POT 151

Inorganic/organic semiconductor heteroepitaxy - towards new hybrid systems for optoelectronics and photonics — •Sylke Blumstengel — Institute of Physics, Humboldt University Berlin, Newtonstr. 15, 12489 Berlin

This talk summarizes our recent efforts to fabricate heterostructures based on ZnO and various conjugated organic materials as well as to tailor their electronic and optical properties. Growth by molecular beam epitaxy of both material components ensures well-defined interfaces and highest structural quality. A unique feature of ZnO and its ternaries ZnCdO and ZnMgO is that films and quantum structures with very good crystalline and optical properties can be epitaxially grown at low temperatures (50°C!) compatible with the stability of organic materials. Thus, not only organic-on-inorganic, but also inorganic-on-organic epitaxy can be performed. Relevant growth mechanisms are discussed. Interfacial energy level alignment including band-offset engineering via the geometric structure of the molecular layer is presented. Direct electronic coupling of the fundamental excitations (Frenkel and Wannier-Mott excitons) across the interface occurs with coupling constants on the meV-energy scale. The superior optoelectronic function of sandwich-type hybrids is demonstrated by the achievement of stimulated emission of the enclosed organic layer at markedly reduced pump thresholds due to efficient energy transfer from ZnO.