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SYSD: Symposium SKM Dissertation-Prize 2014

SYSD 1: Symposium SKM Dissertation-Prize 2014

SYSD 1.3: Hauptvortrag

Montag, 31. März 2014, 11:50–12:15, CHE 89

Spin injection into GaAs - the spin solar cell and spin photodiode — •Bernhard Endres, Mariusz Ciorga, Maximilian Schmid, Martin Utz, Dominique Bougeard, Dieter Weiss, Christian Back, and Günther Bayreuther — Universität Regensburg

Efficient spin injection into semiconductors is a prerequisite for the realization of spintronic devices which primarily make use of the electron spin orientation for data storage and information processing. In III-V semiconductors, a sizable spin polarization can be created by illumination, requiring circularly polarized light at a well-defined wavelength. In contrast, we demonstrate the spin solar cell effect as a new and efficient method for optical spin generation without these restrictions [1]. A laser beam is used to create electron-hole pairs in a (Ga,Mn)As\n-GaAs p-n-junction and to detect the spin accumulation via the magneto-optic Kerr effect (T=15 K). The photo-voltage causes electrons to tunnel across the narrow barrier from the n-GaAs into the (Ga,Mn)As. Since tunneling into (Ga,Mn)As is spin-dependent, spin-polarized electrons accumulate in the n-GaAs. A second working mode, the spin photodiode effect, is realized by applying a negative voltage to the (Ga,Mn)As contact which drives optically excited spins of reverse polarity from the (Ga,Mn)As conduction band into the GaAs layer. This new approach to convert light of arbitrary polarization into spin current is expected to work at room temperature and allows adaptation to different ferromagnets like Fe on mainstream semiconductors like Si.

[1] B. Endres et al., Nature Commun. 4, 2068 (2013).