Regensburg 2010 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 46: Quantum Dots and Wires: Transport
HL 46.5: Talk
Wednesday, March 24, 2010, 15:00–15:15, H17
Electronic and transport properties of Ge nanoparticle pellets structured by focused ion beam — •Andreas Gondorf, Martin Geller, and Axel Lorke — Universität Duisburg-Essen, Duisburg
Semiconductor nanoparticles are of interest for future electronic and optoelectronic devices, especially low cost, flexible, printable electronics. We investigate here the transport properties (charge carrier concentration and mobility) of Ge nanoparticles, which were synthesized in the gasphase and pressed into pellets. The nanoparticles inside these pellets sinter into a sponge-like structure, that may exhibit unusual magneto-transport properties similar to the strong magnetoresistance observed in nanoporous gold [Fujita, PRL 101, 166601 (2008)]. The measurements are made on directly contacted macroscopic pellets and on Hallbar-microstructures fabricated by a focused ion beam (FIB). In the FIB fabrication process, a lamella is cut out of a pellet and positioned onto a prestructured substrate with metal contacts. The sample is connected with the contacts by deposition of platinum. Finally the disk is etched by FIB into a Hallbar shape. We use I-V and Hall-measurements and find a very weak but measurable Hall-effect and a negative magnetoresistance of about 0.01% at 2.5T. At room temperature, Ge nanoparticles show a charge carrier concentration of about 4·1014 cm−3, comparable to the intrinsic charge carrier concentration in bulk germanium. Ge nanoparticles have a very low mobility of 0.1 cm2/Vs at 25∘C, which is comparable to the mobility of organic semiconductors, so that Ge nanoparticles may be suitable in some applications which are presently based on organic semiconductors.