Berlin 2012 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 76: Heterostructures

HL 76.1: Vortrag

Donnerstag, 29. März 2012, 09:30–09:45, EW 202

(contribution withdrawn) Nanowire heterojunction devices with tunable light emission — •Martin Hetzel, Alois Lugstein, and Emmerich Bertagnolli — Institut für Festkörperelektronik, TU Wien, Floragasse 7, 1040 Wien

The results of synthesis as well as the electrical and optical characterization of a heterojunction device with tunable light emission, based on silicon and germanium nanowires and epitaxially grown on GaAs and InAs, are presented. Nanowire growth was performed by means of a VLS process in a LPCVD reactor with the assistance of either catalytic gold seed particles or a thin gold layer. Both silicon and germanium nanowires with a length of a few microns and a diameter of about 100nm are realized. The results depend strongly on the substrate, for which highly p- and n-doped GaAs as well as highly n-doped InAs are used. After growth, thin layers of aluminium oxide and indium tin oxide (ITO), respectively, are deposited on the surface, thus forming a wrapped gate around the nanowires. Then the samples are coated with photoresist which completely encapsulates the nanowires. Consecutively, the nanowire tops are revealed by an O2/SF6 reactive-ion etch, while optical lithography is used to define top contacts consisting of ITO or gold, respectively. Electrical measurements of individual nanowires as well as of nanowire ensembles reveal characteristic diode-like behavior in dependance on growth epitaxy, substrate type and nanowire material. Optical measurements with a tunable monochromatic light source are discussed as well. It is shown that dependent on wavelength and the applied gate voltage, nanowires can be stimulated to light emission, thus enabling tunable heterojunction devices.