TEM Study on Diffusion Process of NiFe Schottky and MgO/NiFe Tunneling Diodes for Spin Injection in Silicon

Analytical electron microscopy is employed to study the structural properties of NiFe Schottky diodes and NiFe/MgO tunneling diodes after annealing up to 400° C. Electrical characterization revealed a drop of the barrier height for the Schottky diodes, while the tunneling diodes are thermally stable...

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Bibliographic Details
Published in:IEEE transactions on magnetics 2010-06, Vol.46 (6), p.2067-2069
Main Authors: Jehyun Lee, Uhrmann, Thomas, Dimopoulos, Theodoros, Bruckl, Hubert, Fidler, Josef
Format: Article
Language:English
Subjects:
Annealing
Cross-disciplinary physics: materials science
rheology
Diffusion
Diffusion processes
Diodes
Dispersion
Electron microscopy
Exact sciences and technology
Intermetallics
Iron compounds
Magnesium oxide
Magnetism
Materials science
Nickel
Nickel base alloys
Nickel compounds
Other topics in materials science
Physics
Schottky barriers
Schottky diodes
Silicon
spin injection
Spin polarized transport
Transmission electron microscopy
tunnel diodes
Tunneling
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Summary:Analytical electron microscopy is employed to study the structural properties of NiFe Schottky diodes and NiFe/MgO tunneling diodes after annealing up to 400° C. Electrical characterization revealed a drop of the barrier height for the Schottky diodes, while the tunneling diodes are thermally stable. From the cross-sectional TEM images of the Schottky diodes, metal diffusion into Si substrate was found. Investigations of the diffusion using energy dispersive spectroscopy and energy filtered transmission electron microscopy revealed that Ni diffused into the Si substrate to form nickel silicide. Moreover, in some cases, the gold capping layer also diffused into the substrate even deeper than Ni. In the case of the tunneling diodes, metal diffusion was inhibited by the presence of MgO.
ISSN:0018-9464
1941-0069
DOI:10.1109/TMAG.2010.2040594