Holes confined in SiGe nanostructures

DIPC Seminars

Vitaly N. Golovach, CEA Grenoble, Francia
Donostia International Physics Center (DIPC).Paseo Manuel de Lardizabal, 4 (nearby the Facultad de Quimica), Donostia
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Holes confined in SiGe nanostructures Holes confined in SiGe nanocrystals have recently been studied in dc transport measurements [1]. Motivated by the experimental work, I will discuss two novel effects related to the valence band of the semiconductor and compare the theory to the experiment. As the first effect, I will show that the spin-orbital splitting of the valence band gives rise to spin-selective tunneling from the nanocrystal into a metallic lead. The explanation of this phenomenon is based on an expansion of the Luttinger Hamiltonian around the 2D limit and a phenomenological approach to tunneling at the metal-semiconductor interface. The conclusions drawn from the theory are in excellent agreement with the experimental results [2]. As the second effect, I will consider the g-factor of the hole confined in the SiGe nanocrystal and study its dependence on an electric field applied along the growth direction. I will discuss contributions to the heavy-hole g-factor and effective mass, previously overlooked in the literature. I will formulate a novel mechanism of g-factor control for holes. In an outlook, I will relate the spin-splitting in SiGe self-assembled structures to the physics of Majorana fermions. [1] G. Katsaros et al., Nature Nanotech. 5, 458 (2010). [2] G. Katsaros et al., Phys. Rev. Lett. 107, 246601 (2011).