Wednesday 26 January; Delft, G. Katsaros & S. De Franceschi "Spins in Si-Ge nanostructures"



Time: 11:00 hrs

Location: Room E

1: INAC/SPSMS/LaTEQS, CEA-UJF Grenoble, 17 rue des Martyrs, 38054 Grenoble, France
2: IFW-Dresden/ Institute for Integrative Nanosciences, Helmholtzstr. 20, 01069 Dresden, Germany

Nanostructured materials such as semiconductor nanowires and self-assembled quantum dots offer a variety of opportunities to create relatively simple and tunable electronic systems in which single electronic spins can be confined and manipulated. Such systems provide a test bench for the development of devices with spin-based functionalities with possible implications for quantum information processing and communication.
In this talk, we shall consider single quantum-dot systems obtained by contacting individual Si-Ge nanostructures such as nanowires and self-assembled islands. These materials are chosen in view of their potentially long time scales for spin coherence.
First part (De Franceschi):
We shall present recent progress on the study of single-impurity effects in silicon nanowires. In particular: tunneling through a single spin-1/2 impurity in ultra-short-channel (<10 nm) devices; a first study of single-impurity spin relaxation in a silicon nanowire.  Both bottom-up and top-down nanowires have been considered for these experiments. In the first case, a new method for the realization of controlled silicide contacts has been developed.

Second part (Katsaros):
We shall present tunneling and cotunneling spectroscopy measurements in single quantum dots made from individually contacted SiGe self-assembled islands. These measurements provide accurate information on the spin-related properties of the confined hole states. In particular, we find hole g-factors are strongly anisotropic and tunable by means of an external electric field. In the cotunneling regime we also observe interesting asymmetries in the current-voltage characteristics providing additional evidence of a strong spin-orbit interaction.