Interface bonding of a ferromagnetic/semiconductor junction : a photoemission study of Fe/ZnSe(001)

We have probed the interface of a ferromagnetic/semiconductor (FM/SC) heterojunction by a combined high resolution photoemission spectroscopy and x-ray photoelectron diffraction study. Fe/ZnSe(001) is considered as an example of a very low reactivity interface system and it expected to constitute large Tunnel Magnetoresistance devices. We focus on the interface atomic environment, on the microscopic processes of the interface formation and on the iron valence-band. We show that the Fe contact with ZnSe induces a chemical conversion of the ZnSe outermost atomic layers. The main driving force that induces this rearrangement is the requirement for a stable Fe-Se bonding at the interface and a Se monolayer that floats at the Fe growth front. The released Zn atoms are incorporated in substitution in the Fe lattice position. This formation process is independent of the ZnSe surface termination (Zn or Se). The Fe valence-band evolution indicates that the d-states at the Fermi level show up even at submonolayer Fe coverage but that the Fe bulk character is only recovered above 10 monolayers. Indeed, the Fe 1-band states, theoretically predicted to dominate the tunneling conductance of Fe/ZnSe/Fe junctions, are strongly modified at the FM/SC interface.Comment: 23 pages, 5 figures, submitted to Physical review

First Principles Calculations of Fe on GaAs (100)

We have calculated from first principles the electronic structure of 0.5 monolayer upto 5 monolayer thick Fe layers on top of a GaAs (100) surface. We find the Fe magnetic moment to be determined by the Fe-As distance. As segregates to the top of the Fe film, whereas Ga most likely is found within the Fe film. Moreover, we find an asymmetric in-plane contraction of our unit-cell along with an expansion perpendicular to the surface. We predict the number of Fe 3d-holes to increase with increasing Fe thickness on $p$-doped GaAs.Comment: 9 pages, 14 figures, submitted to PR

Ion channeling and x-ray diffraction studies of epitaxial Fe on GaAs(001)

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Formation of a body-centered-cubic Fe-based alloy at the Fe ∕ GaAs(001) interface

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Residual Stresses and Magnetoelastic Coupling in Ultrathin Fe Films Deposited on GaAs(001)

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Epitaxial growth of Fe films on cubic GaN(001)

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Interface formation and structural properties of iron films on Al0.48_{0.48} In0.52_{0.52}As(001)

Using reflection high-energy electron diffraction as well as ultraviolet and X-ray photoemission spectroscopy we have investigated the growth of epitaxial Fe ultrathin films onto Al$_{0.48}$In$_{0.52}$(001)-($2\times 4$) surface. The Fe films grow in a body centered cubic (bcc) structure with epitaxial relationship Fe(001)//Al$_{0.48}$In$_{0.52}$As(001). The analysis of the photoemission data demonstrates that Fe atoms react with the Al$_{0.48}$In$_{0.52}$As substrate. In and As atoms, liberated during the first stage of the growth, tend to segregate at the films surface while reacting Al atoms are accommodated in an interfacial alloy. The Fermi level pinning position at the Fe/Al$_{0.48}$In$_{0.52}$As(001) interface, determined from the photoemission results, is found 0.76 +/- 0.08 eV below the conduction band minimum

Fe3GaAs/GaAs(0 01): a stable and magnetic metal-semiconductor heterostructure

International audienceWe show that in agreement with the ternary Fe–Ga–As phase diagram, the solid-state interdiffusions in epitaxial Fe/GaAs(0 0 1) heterostructures lead, at a temperature of approximately 500 °C, to the formation of thermodynamically stable Fe3GaAs/GaAs(0 0 1) contacts quite similar to the well-known silicide/Si ones. The Fe3GaAs films are made of grains epitaxial on GaAs with a well-defined interface. Their magnetic and electrical properties make Fe3GaAs on GaAs an attractive metallization scheme for future magnetoelectronic devices. The results we report concern (25 or 80 nm Fe)/GaAs(0 0 1) heterostructures annealed at 480 and 500 °C for 10 min and characterized ex situ by He+ Rutherford backscattering and ion channeling, X-ray diffraction, transmission electron microscopy and alternating gradient field magnetometry