Berlin 2008 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 35: Spin controlled transport II
HL 35.9: Vortrag
Mittwoch, 27. Februar 2008, 16:30–16:45, ER 164
Spin-dependent transport in Si quantum dots — •Konrad Klein1, Rui N. Pereira1, Andre R. Stegner1, Hartmut Wiggers2, Martin S. Brandt1, and Martin Stutzmann1 — 1Walter Schottky Institut, Technische Universität München, Garching — 2Universität Duisburg-Essen, Inst. for Combustion and Gas Dynamics, Duisburg
Phosphorus-doped silicon nanocrystals (Si-ncs) can be used as a model system for studying the electronic transport through doped quantum dots. Electrically-detected magnetic resonance (EDMR) is employed to study the spin-dependent transport in thin films composed of Si-ncs with diameters in the range 4-50nm. We have recently demonstrated that Si dangling bonds and substitutional phosphorus donors contribute to electronic transport through films composed of large ensembles of doped and undoped Si-ncs. As a more detailed understanding of the fundamental transport mechanisms in Si-ncs can only be obtained using a small number of nanocrystals, we have developed methods to perform EDMR measurements on a very small number of Si-ncs. The results of downscaled samples and those observed for large networks of Si-ncs, e.g. quantum-confinement causing an enhancement of the coupling between the electron and the nuclear spin of 31P, are discussed. Already for Si-ncs with a diameter of 17 nm, we observe a significant confinement-induced enhancement of the 31P hyperfine coupling constant by 15% with respect to the bulk value. This is in clear contrast to changes observed in optical transitions such as the bandgap or luminescence peak positions, for which a significant increase is only observed for nanocrystal diameters below 5 nm.