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O: Fachverband Oberflächenphysik

O 7: Plasmonics and Nanooptics I

O 7.10: Vortrag

Montag, 11. März 2013, 12:45–13:00, H31

Nanoantenna supported internal photoemission in metal-isolator-metal junctions — Dieter Akemeier¹, Detlef Diesing², Dominik Differt¹, Adelheid Godt³, Ingo Heesemann³, •Matthias Hensen¹, Andreas Hütten¹, Walter Pfeiffer¹, and Christian Strüber¹ — ¹Fakultät für Physik, Universität Bielefeld, Universitätsstr. 25, 33615 Bielefeld, Germany — ²Fakultät für Chemie, Universität Duisburg-Essen, Universitätsstr. 5, 45141 Essen, Germany — ³Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, 33615 Bielefeld, Germany

Thin-film metal-isolator-metal (MIM) heterosystems, i.e. Ta-TaO_x-Ag and Ta-TaO_x-Au junctions, are investigated as devices for ultrafast nanoscale electron injection in nanophotonic applications. Internal photoemission (IPE) microscopy provides lateral maps of the induced multiphoton photocurrents that are excited by few-cycle pulses from a Ti:Sapphire laser (6 fs). Nanostructures acting as optical antennas are prepared on the Ag top electrode by deposition of Au nanoparticles and Au nanoparticle aggregates or by means of local focussed ion beam milling. The multiphoton internal photoemission current is strongly enhanced in the vicinity of these nanoantennas. Based on FDTD model calculations (a grid-based differential time-domain numerical modeling method) this enhancement is attributed to field enhancement effects in the MIM structure.