Dresden 2014 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 30: Poster: Quantum dots and wires: Preparation, characterization, optical properties and transport

HL 30.13: Poster

Montag, 31. März 2014, 17:00–20:00, P2

Electronic Structure and Photoluminescence of Bare Core and Core/shell CdSe QDs — •Ghazal Tofighi1, Martin Möbius2, Jörg Martin3, Christian Spudat3, Thomas Otto2, Thomas Gessner2,3, Ovidiu D. Gordan1, and Dietrich R.T. Zahn11Technische Universität Chemnitz, Semiconductor Physics, Chemnitz, Germany — 2Technische Universität Chemnitz, ZfM, Chemnitz, Germany — 3Fraunhofer Institute for Electronic Nano Systems, Chemnitz, Germany

CdSe quantum dots (QDs) exhibit interesting properties including narrow emission bands, good photostability, and bright photoluminescence (PL) which can be tuned by the size of QDs and surface ligands. Therefore, we can integrate them with piezoelectric materials in order to make extremely small film-based sensors. Electrical charges generated by mechanical stress within the piezoelectric film can be injected into QDs, resulting in quenching their photoluminescence. Subsequently, e.g. material failure could thus be detected at an early stage through a color change of the photoluminescence.

For this purpose, we prepared thin layers of CdSe (core) and CdSe/ZnS (core/shell) QDs on gold substrates using the Langmuir-Blodgett method and investigated the electronic structure of QDs by photoemission spectroscopy (PES) and inverse photoemission spectroscopy (IPS). Furthermore, PL measurement and Raman spectroscopy were also performed on the QD layers, and the optical band gap was compared to the electronic band gap achieved from the IPS/UPS measurements.

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