B. Jenichen - Academia.edu (original) (raw)
Papers by B. Jenichen
Journal of Applied Physics, 1993
Applied Physics Letters, 2013
Journal of Physics D: Applied Physics, 1999
High resolution x-ray diffractometry and photoluminescence measurements (PL) have been used to co... more High resolution x-ray diffractometry and photoluminescence measurements (PL) have been used to compare the effects of elastic stress relaxation of free standing and overgrown Ga0.22In0.78As0.80P0.20 quantum wire structures on InP. The elastic relaxation occurs near the free surface of the sidewalls resulting only in a minor shift of the PL line. The overgrowth of the structures with a Ga0.22In0.78As0.16P0.84 layer, which has a residual tensile strain of more than 1% compared with the InP substrate, leads to a strong increase of the PL line shift. At the same time, a shift of the x-ray diffraction pattern from the small angle side of the InP peak to the large angle side is observed. In addition, the diffuse scattering increases. The strain fields in the wire structures are calculated, and the diffraction patterns are determined from the strain maps in the kinematical approximation.
Semiconductor Science and Technology, 2019
We investigate the formation of lattice matched single-crystalline Fe3Si/GaAs(001) ferromagnet/se... more We investigate the formation of lattice matched single-crystalline Fe3Si/GaAs(001) ferromagnet/semiconductor hybrid structures by Volmer–Weber island growth, starting from the epitaxial growth of isolated Fe3Si islands up to the formation of continuous films as a result of island coalescence. We find coherent defect-free layers exhibiting compositional disorder near the Fe3Si/GaAs—interface for higher growth rates, whereas they are fully ordered for lower growth rates.
Investigation of the thickness dependence of the magnetic anisotropy in B2-type Co2TiSi films on ... more Investigation of the thickness dependence of the magnetic anisotropy in B2-type Co2TiSi films on GaAs(001), shows a pronounced perpendicular magnetic anisotropy at 10 K for thicknesses up to 13.5 nm. We have evidenced that the interfacial anisotropy induced by interface clusters has a strong influence on the perpendicular magnetic anisotropy of this hybrid structure, especially at temperatures lower than the blocking temperature of the clusters (28 K). However, as this influence can be ruled out at higher temperatures, the perpendicular magnetic anisotropy which is found to persist up to room-temperature can be ascribed to the magnetic properties of the Co2TiSi films. For thicknesses larger than 15.0 nm, we observe an alignment of the magnetic easy axis parallel to the sample surface, which is most likely due to the shape anisotropy and the film structure.
GaAs/Fe3Si core/shell nanowire structures were fabricated by molecular-beam epitaxy on oxidized S... more GaAs/Fe3Si core/shell nanowire structures were fabricated by molecular-beam epitaxy on oxidized Si(111) substrates and investigated by synchrotron x-ray diffraction. The surfaces of the Fe3Si shells exhibit nanofacets. These facets consist of well pronounced Fe3Si{111} planes. Density functional theory reveals that the Si-terminated Fe3Si{111} surface has the lowest energy in agreement with the experimental findings. We can analyze the x-ray diffuse scattering and diffraction of the ensemble of nanowires avoiding the signal of the substrate and poly-crystalline films located between the wires. Fe3Si nanofacets cause streaks in the x-ray reciprocal space map rotated by an azimuthal angle of 30° compared with those of bare GaAs nanowires. In the corresponding TEM micrograph the facets are revealed only if the incident electron beam is oriented along [1 1 ̄ 0] in accordance with the x-ray results. Additional maxima in the x-ray scans indicate the onset of chemical reactions between Fe3...
Semiconductor Science and Technology, 2018
Journal of Applied Physics, 2016
Semiconductor Science and Technology, 2006
Physical Review B, 2005
As-grown thin epitaxial Fe 3 Si films fabricated by molecular beam epitaxy on GaAs͑001͒ are studi... more As-grown thin epitaxial Fe 3 Si films fabricated by molecular beam epitaxy on GaAs͑001͒ are studied by grazing incidence x-ray diffraction. The long-range order parameters of the films of different stoichiometry are determined by measuring fundamental and superlattice crystal truncation rods and comparing them to simulations in dynamical approximation. Two order parameters, associated with the degree of migration of Si atoms into different Fe sublattices, are obtained. A residual intermixing of the sublattices is found, even near complete stoichiometry. The relative positions of the Fe 3 Si and GaAs lattices are determined. Fe atoms in Fe 3 Si are located at the positions of the Ga atoms in GaAs, with an additional shift of 0.1± 0.04 Å of the tetragonally distorted Fe 3 Si lattice normal to the interface.
Journal of Crystal Growth, 1999
Journal of Applied Physics, 2002
Journal of Applied Physics, 2001
Journal of Applied Physics, 1997
Applied Physics Letters, 2002
Acta Crystallographica Section A Foundations of Crystallography, 2005
Physical Review B, 2003
The structure of phase-separated ͑Ga, Mn͒As, annealed at high temperature (ϳ700°C), is studied by... more The structure of phase-separated ͑Ga, Mn͒As, annealed at high temperature (ϳ700°C), is studied by x-ray diffraction techniques. Analysis of the x-ray diffuse and coherent scattering reveals two types of clusters: ͑1͒ small clusters detected by diffuse scattering through the distortions they produce in the host matrix and ͑2͒ larger clusters with MnAs structure giving rise to coherent diffraction peaks. The average sizes for the two cluster types are estimated to be 5 and 18 nm, respectively. The smaller clusters are found to be of vacancy type. Their density is estimated to be 1.8ϫ10 16 cm Ϫ3. The hexagonal lattice of the larger MnAs crystallites is found to be compressed along the ͓2 110͔ direction by Ϫ0.49% with respect to the bulk hexagonal MnAs lattice. The host zinc blende matrix is found to be under a Ϫ0.20% tensile strain.
Semiconductor Science and Technology, 2014
Journal of Applied Physics, 1993
Journal of Applied Physics, 1993
Applied Physics Letters, 2013
Journal of Physics D: Applied Physics, 1999
High resolution x-ray diffractometry and photoluminescence measurements (PL) have been used to co... more High resolution x-ray diffractometry and photoluminescence measurements (PL) have been used to compare the effects of elastic stress relaxation of free standing and overgrown Ga0.22In0.78As0.80P0.20 quantum wire structures on InP. The elastic relaxation occurs near the free surface of the sidewalls resulting only in a minor shift of the PL line. The overgrowth of the structures with a Ga0.22In0.78As0.16P0.84 layer, which has a residual tensile strain of more than 1% compared with the InP substrate, leads to a strong increase of the PL line shift. At the same time, a shift of the x-ray diffraction pattern from the small angle side of the InP peak to the large angle side is observed. In addition, the diffuse scattering increases. The strain fields in the wire structures are calculated, and the diffraction patterns are determined from the strain maps in the kinematical approximation.
Semiconductor Science and Technology, 2019
We investigate the formation of lattice matched single-crystalline Fe3Si/GaAs(001) ferromagnet/se... more We investigate the formation of lattice matched single-crystalline Fe3Si/GaAs(001) ferromagnet/semiconductor hybrid structures by Volmer–Weber island growth, starting from the epitaxial growth of isolated Fe3Si islands up to the formation of continuous films as a result of island coalescence. We find coherent defect-free layers exhibiting compositional disorder near the Fe3Si/GaAs—interface for higher growth rates, whereas they are fully ordered for lower growth rates.
Investigation of the thickness dependence of the magnetic anisotropy in B2-type Co2TiSi films on ... more Investigation of the thickness dependence of the magnetic anisotropy in B2-type Co2TiSi films on GaAs(001), shows a pronounced perpendicular magnetic anisotropy at 10 K for thicknesses up to 13.5 nm. We have evidenced that the interfacial anisotropy induced by interface clusters has a strong influence on the perpendicular magnetic anisotropy of this hybrid structure, especially at temperatures lower than the blocking temperature of the clusters (28 K). However, as this influence can be ruled out at higher temperatures, the perpendicular magnetic anisotropy which is found to persist up to room-temperature can be ascribed to the magnetic properties of the Co2TiSi films. For thicknesses larger than 15.0 nm, we observe an alignment of the magnetic easy axis parallel to the sample surface, which is most likely due to the shape anisotropy and the film structure.
GaAs/Fe3Si core/shell nanowire structures were fabricated by molecular-beam epitaxy on oxidized S... more GaAs/Fe3Si core/shell nanowire structures were fabricated by molecular-beam epitaxy on oxidized Si(111) substrates and investigated by synchrotron x-ray diffraction. The surfaces of the Fe3Si shells exhibit nanofacets. These facets consist of well pronounced Fe3Si{111} planes. Density functional theory reveals that the Si-terminated Fe3Si{111} surface has the lowest energy in agreement with the experimental findings. We can analyze the x-ray diffuse scattering and diffraction of the ensemble of nanowires avoiding the signal of the substrate and poly-crystalline films located between the wires. Fe3Si nanofacets cause streaks in the x-ray reciprocal space map rotated by an azimuthal angle of 30° compared with those of bare GaAs nanowires. In the corresponding TEM micrograph the facets are revealed only if the incident electron beam is oriented along [1 1 ̄ 0] in accordance with the x-ray results. Additional maxima in the x-ray scans indicate the onset of chemical reactions between Fe3...
Semiconductor Science and Technology, 2018
Journal of Applied Physics, 2016
Semiconductor Science and Technology, 2006
Physical Review B, 2005
As-grown thin epitaxial Fe 3 Si films fabricated by molecular beam epitaxy on GaAs͑001͒ are studi... more As-grown thin epitaxial Fe 3 Si films fabricated by molecular beam epitaxy on GaAs͑001͒ are studied by grazing incidence x-ray diffraction. The long-range order parameters of the films of different stoichiometry are determined by measuring fundamental and superlattice crystal truncation rods and comparing them to simulations in dynamical approximation. Two order parameters, associated with the degree of migration of Si atoms into different Fe sublattices, are obtained. A residual intermixing of the sublattices is found, even near complete stoichiometry. The relative positions of the Fe 3 Si and GaAs lattices are determined. Fe atoms in Fe 3 Si are located at the positions of the Ga atoms in GaAs, with an additional shift of 0.1± 0.04 Å of the tetragonally distorted Fe 3 Si lattice normal to the interface.
Journal of Crystal Growth, 1999
Journal of Applied Physics, 2002
Journal of Applied Physics, 2001
Journal of Applied Physics, 1997
Applied Physics Letters, 2002
Acta Crystallographica Section A Foundations of Crystallography, 2005
Physical Review B, 2003
The structure of phase-separated ͑Ga, Mn͒As, annealed at high temperature (ϳ700°C), is studied by... more The structure of phase-separated ͑Ga, Mn͒As, annealed at high temperature (ϳ700°C), is studied by x-ray diffraction techniques. Analysis of the x-ray diffuse and coherent scattering reveals two types of clusters: ͑1͒ small clusters detected by diffuse scattering through the distortions they produce in the host matrix and ͑2͒ larger clusters with MnAs structure giving rise to coherent diffraction peaks. The average sizes for the two cluster types are estimated to be 5 and 18 nm, respectively. The smaller clusters are found to be of vacancy type. Their density is estimated to be 1.8ϫ10 16 cm Ϫ3. The hexagonal lattice of the larger MnAs crystallites is found to be compressed along the ͓2 110͔ direction by Ϫ0.49% with respect to the bulk hexagonal MnAs lattice. The host zinc blende matrix is found to be under a Ϫ0.20% tensile strain.
Semiconductor Science and Technology, 2014
Journal of Applied Physics, 1993