Berlin 2012 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 91: Poster Session: Spintronics / Magnetic Semiconductors / Transport

HL 91.14: Poster

Donnerstag, 29. März 2012, 16:00–19:00, Poster D

Spin-splitting and g-factor of confined hole states in differently strained Ge quantum dots — •Alexei B. Agafonov, Kai-Martin Haendel, and Rolf J. Haug — Institut für Festkörperphysik, Leibniz Universität Hannover, Appelstraße 2, D-30167 Hannover, Germany

In this work we have investigated experimentally hole transport through vertical resonant tunneling structures of different lateral dimensions of the order of 1 micron using resonant magnetotunneling spectroscopy at low temperatures. The studied samples were prepared from the same double-barrier Si/Ge heterostructure containing Ge quantum dots sandwiched between two Si tunnel barriers.

For a smaller sample a considerable shift in the voltage position of current resonances arising in its current-voltage characteristic (IVC) at high bias in comparison with the position of the correspondent resonances in the IVC of a bigger one was found. This shift indicates a partial relaxation of the built-in strain in Ge layer of the smaller sample caused by the decrease of its lateral dimensions.

It was also found that the downscaling of the sample lateral size gives rise to a noticeable variation of g-factor of heavy hole states confined in quantum dots. The g-factor values were obtained from the splitting of the differential conductance peaks under the influence of the static homogeneous magnetic field. This splitting reflects the Zeeman spin-splitting of the above mentioned states and turned out to be field orientation dependent. The observed difference in g-factor is attributed to the partial strain relaxation in Ge layer of the samples as well.