Growth, structure and morphology of epitaxial Fe(0 0 1) films on GaAs(0 0 1)c(4 × 4)

Abstract

We studied epitaxy, growth, structure and morphology of thin Fe(0 0 1) films on the As-rich GaAs(0 0 1)-c(4 × 4) surface, deposited by molecular beam epitaxy at growth temperatures between room temperature and 250° C. Electron and x-ray diffraction (XRD) techniques evidence epitaxial growth with Fe(0 0 1)[1 0 0] ∥ GaAs(0 0 1)[1 0 0]. The residual strain derived from the XRD results is consistent with recent stress measurements. Cross-sectional transmission electron microscopy reveals an abrupt interface for room-temperature films and the formation of a ∼10 nm thick crystalline Fe-Ga-As intermediate layer at 250° C. The dependence of the surface morphology on growth temperature and annealing evidences a kinetic roughening of the Fe surface at growth temperatures of 100-200° C due to the presence of step-edge barriers.

Effect of low-temperature post-growth annealing on anisotropic strain in epitaxial Fe layers deposited on GaAs(001)

“…By analyzing both symmetric (004) and asymmetric scans ((224), (À224)), we obtain the deformation of elementary cells in the crystalline layers. This approach complements previous studies 18,23 which use only the out-of-plane lattice constant to evaluate strain in thicker Fe films. The RSM's are shown as colour maps of diffraction intensity plotted as a function of reciprocal space coordinates (q z , q y ).…”

Ultrathin MgO diffusion barriers for ferromagnetic electrodes on GaAs(001)

“…The change in pattern from sharp spots lying on the Laue circle of the GaAs substrate to a spotty pattern interconnected by broad vertical streaks upon MgO deposition implies the formation of a corrugated surface, in accordance with the HRTEM results. Subsequent growth of the Fe film on MgO is also crystalline; however, its RHEED patterns are degraded because of a kinetic surface roughening of the epitaxial Fe film due to the presence of step-edge barriers [38,42].…”

Interface structure and composition of MoO3/GaAs(0 0 1)

“…The MoO 3 films were deposited onto c(4 × 4) reconstructed GaAs(0 0 1) substrates mounted on a cantileverbeam device. They were prepared in the III/V growth chamber by standard routine (for details see [44]). The c(4 × 4) reconstruction of GaAs(0 0 1) was confirmed by reflection high energy electron diffraction (RHEED) in the III/V chamber and, after transfer to the As-free metal/oxide chamber without breaking the ultrahigh vacuum conditions, by low energy electron diffraction (LEED) [44].…”

“…They were prepared in the III/V growth chamber by standard routine (for details see [44]). The c(4 × 4) reconstruction of GaAs(0 0 1) was confirmed by reflection high energy electron diffraction (RHEED) in the III/V chamber and, after transfer to the As-free metal/oxide chamber without breaking the ultrahigh vacuum conditions, by low energy electron diffraction (LEED) [44]. The MoO 3 films were prepared by thermal evaporation of MoO 3 powder out of a Mo crucible within 45 min after the sample transfer; the pressure during deposition was 5 × 10 −10 mbar, the deposition rate was 0.06-0.08 nm s −1 as controlled by a quartz crystal microbalance (QCM) calibrated by a QCM in substrate position.…”