AVS 47th International Symposium
    Magnetic Interfaces and Nanostructures Wednesday Sessions
       Session MI+EL-WeM

Paper MI+EL-WeM7
Characterizations of Fe Thin Films on GaAs (001) Grown at Cryogenic Temperatures by Molecular Beam Epitaxy

Wednesday, October 4, 2000, 10:20 am, Room 206

Session: Magnetic Semiconductors and Hybrid Structures I
Presenter: Y. Chye, University of California, Santa Barbara
Authors: Y. Chye, University of California, Santa Barbara
P Petroff, University of California, Santa Barbara
Correspondent: Click to Email
One of our research objectives is to fabricate hybrid structures by integrating ferromagnetic materials into semiconductors. It has been demonstrated that molecular beam epitaxy (MBE) can be used to fabricate single crystalline Fe directly upon GaAs.@footnote 1@ However, the intermixing between Fe and GaAs at the interface forms a "magnetically dead layer"@footnote 1@ which will badly affect polarized transport and thus make efficient "spintronics" devices hard to realize. In an effort to circumvent this problem, we propose to grow Fe on GaAs at cryogenic temperatures (below -100 ° C). At these temperatures, the deposited Fe atoms and the GaAs surface atoms are less likely to react with each other through interdiffusion. To implement these ideas, we grow Fe thin films on GaAs (001) semi-insulating substrates at -150 ° C in an EPI-620 MBE with a liquid-nitrogen cooled sample stage. It is indicated by the streaky RHEED pattern that single crystalline Fe is grown on GaAs. The surface morphology, interface properties, crystal structure, film orientation and magnetic behavior of the samples have been characterized by atomic force microscopy (AFM), transmission electron microscopy (TEM), x-ray diffraction, and superconductivity quantum interference device (SQUID), respectively. To examine the interdiffusion at the interface, we perform photoluminescence (PL) measurements for samples with very thin Fe films grown at different temperatures above GaAs quantum wells. Our results show that the PL peaks for the quantum wells do not significantly change for the cryogenic temperature grown samples, whereas the room temperature grown samples show a dramatically reduced luminescence efficiency and energy emission shift. These results suggest that the cryogenic temperature deposition strongly suppress the interdiffusion between the Fe and GaAs at the interface. @FootnoteText@ @footnote 1@ J. J. Krebs, B. T. Jonker, G. A. Prinz, J. Appl. Phys., 61 (1987) 2596.