Growth and Properties of Ferromagnet-SemiconDuctor Hetero-Structures for Spin Injection

• Published in: Phase transitions 2003-01, Vol.76 (4-5), p.445-458
• Main Authors: Däweritz, L., Ramsteiner, M., Trampert, A., Kästner, M., Schippan, F., Schönherr, H.-P., Jenichen, B., Ploog, K. H.
• Format: Article
• Language: English
• Subjects: Ferromagnet-semiconductor Hybrid Structures; Interfaces; Mnas; Molecular Beam Epitaxy; Spin Injection
• ISSN: 0141-1594; 1029-0338
• DOI: 10.1080/0141159021000051352

Molecular-beam epitaxial growth and interface formation is investigated and optimized for the material systems Fe-on-GaAs(001) and MnAs-on-GaAs(001), which represent model systems for the integration of magnetic materials with semiconductors and the investigation of spin injection. In view of interface reactions as a key problem for the first system and in order to optimize the surface morphology, the Fe films are grown at reduced temperature. For MnAs-on-GaAs, an abrupt interface with an anisotropic lattice-mismatch accommodation mechanism is observed, which explains the unexpected high quality of the films. It is shown that the phase transition between paramagnetic g MnAs and ferromagnetic f MnAs during cooling after growth plays an important role and leads, at appropriate conditions, to strain-mediated self-organized structures. Electrical injection of spin polarized electrons through the ferromagnet-semiconductor interfaces is observed by analyzing the electroluminescence signal of GaAs/(In, Ga)As light emitting diodes capped with Fe or MnAs.