Thickness Dependent Tetragonal Relaxation of Iron in Epitaxial Fe/Pd Multilayer Films

2000 ◽  
Vol 619 ◽  
Author(s):  
T. Steffl ◽  
B. Rellinghaus ◽  
H. Mühlbauer ◽  
CH. Müller ◽  
H. Herper ◽  
...  
Keyword(s):  
Layer Thickness ◽  
Lattice Relaxation ◽  
Lattice Parameter ◽  
Growth Direction ◽  
Atomic Volume ◽  
Subsequent Growth ◽  
Structural Investigations ◽  
Sapphire Substrates ◽  
Plane Lattice ◽  
Out Of Plane

ABSTRACTWe have prepared (Fe(001)/Pd(001)) multilayers onto Pd-buffered sapphire substrates. Structural investigations utilizing HRTEM, RHEED and XRD show that the films grow epitaxially for up to 32 bilayers. Whereas the Fe lattice is found to assume the lateral (in-plane) lattice spacing of the underlying Pd layers, the out-of-plane lattice parameter along the [001] growth direction of the film is successively reduced with increasing Fe layer thickness. This outof-plane lattice relaxation even survives a subsequent growth of Pd onto the Fe. Thus, by varying the Fe layer thickness we have control of the atomic volume of Fe. Magnetization measurements reveal that the magnetic moment of Fe is as high as 2.7 µB per atom when the atomic volume is larger than Vat(Fe) ≥ 11.7 Å3 and is reduced to 2.2 µB per atom for Vat(Fe) ≤ 11.1 Å3.

Damage and Lattice Strain in Ion-Irradiated AlxGai-xAs

1994 ◽  
Vol 354 ◽  
Author(s):  
P. Partyka ◽  
R.S. Averback ◽  
D.V. Forbes ◽  
J.J. Coleman ◽  
P. Ehrhart ◽  
...  
Keyword(s):  
Rutherford Backscattering Spectrometry ◽  
Lattice Parameter ◽  
Large Strains ◽  
X Ray Diffraction ◽  
Al Content ◽  
Plane Lattice ◽  
Transmission Electron ◽  
Out Of Plane ◽  
Radiation Induced ◽  
High Al Content

AbstractRadiation-induced damage and strain in AlxGai-xAs (x=5 to 1) were investigated by measurements of the lattice parameter using x-ray diffraction. Irradiations employed MeV C, Ar and Au ion beams with a substrate temperature of 80 K. For samples with high Al content, the out-of-plane lattice parameter increased with fluence at low doses, saturated, and then decreased to nearly its original value. The in-plane lattice parameter did not change, throughout. These results were independent of the irradiation particle when scaled by damage energy. For the Al.5Ga.5As samples, however, the out-of-plane lattice parameter increased monotonically with dose to large strains until the layer amorpnized. Selected samples were examined by high resolution and conventional transmission electron microscopy (TEM). Channeling Rutherford backscattering spectrometry (CRBS) was also employed to monitor the buildup of damage in many samples. Recovery of the lattice parameter during subsequent thermal annealing was also investigated.

LaNiO3 films with tunable out-of-plane lattice parameter and their strain-related electrical properties

2015 ◽  
Vol 212 (9) ◽  
pp. 1925-1930 ◽  
Author(s):  
Haoming Wei ◽  
Marcus Jenderka ◽  
Marius Grundmann ◽  
Michael Lorenz
Keyword(s):  
Electrical Properties ◽  
Lattice Parameter ◽  
Plane Lattice ◽  
Out Of Plane

Structure and Orientation of As Precipitates in LT-MBE Grown GaAs

1991 ◽  
Vol 49 ◽  
pp. 900-901 ◽  
Author(s):  
Alain Claverie ◽  
Zuzanna Liliental-Weber
Keyword(s):  
Transport Properties ◽  
Layer Thickness ◽  
Growth Temperature ◽  
Low Temperatures ◽  
Lattice Parameter ◽  
Crystalline Quality ◽  
Insulating Properties ◽  
Lt Gaas

GaAs layers grown by MBE at low temperatures (in the 200°C range, LT-GaAs) have been reported to have very interesting electronic and transport properties. Previous studies have shown that, before annealing, the crystalline quality of the layers is related to the growth temperature. Lowering the temperature or increasing the layer thickness generally results in some columnar polycrystalline growth. For the best “temperature-thickness” combinations, the layers may be very As rich (up to 1.25%) resulting in an up to 0.15% increase of the lattice parameter, consistent with the excess As. Only after annealing are the technologically important semi-insulating properties of these layers observed. When annealed in As atmosphere at about 600°C a decrease of the lattice parameter to the substrate value is observed. TEM studies show formation of precipitates which are supposed to be As related since the average As concentration remains almost unchanged upon annealing.

The limits of strain and lattice parameter measurements by CBED

1989 ◽  
Vol 47 ◽  
pp. 518-519
Author(s):  
Hamish L. Fraser
Keyword(s):  
Electron Beam ◽  
Mirror Symmetry ◽  
Local Symmetry ◽  
Lattice Parameter ◽  
Growth Direction ◽  
Surface Relaxation ◽  
Strained Layer ◽  
Axis Parallel ◽  
Local Lattice ◽  
Strained Layer Superlattice

The topic of strain and lattice parameter measurements using CBED is discussed by reference to several examples. In this paper, only one of these examples is referenced because of the limitation of length. In this technique, scattering in the higher order Laue zones is used to determine local lattice parameters. Work (e.g. 1) has concentrated on a model strained-layer superlattice, namely Si/Gex-Si1-x. In bulk samples, the strain is expected to be tetragonal in nature with the unique axis parallel to [100], the growth direction. When CBED patterns are recorded from the alloy epi-layers, the symmetries exhibited by the patterns are not tetragonal, but are in fact distorted from this to lower symmetries. The spatial variation of the distortion close to a strained-layer interface has been assessed. This is most readily noted by consideration of Fig. 1(a-c), which show enlargements of CBED patterns for various locations and compositions of Ge. Thus, Fig. 1(a) was obtained with the electron beam positioned in the center of a 5Ge epilayer and the distortion is consistent with an orthorhombic distortion. When the beam is situated at about 150 nm from the interface, the same part of the CBED pattern is shown in Fig. 1(b); clearly, the symmetry exhibited by the mirror planes in Fig. 1 is broken. Finally, when the electron beam is positioned in the center of a 10Ge epilayer, the CBED pattern yields the result shown in Fig. 1(c). In this case, the break in the mirror symmetry is independent of distance form the heterointerface, as might be expected from the increase in the mismatch between 5 and 10%Ge, i.e. 0.2 to 0.4%, respectively. From computer simulation, Fig.2, the apparent monocline distortion corresponding to the 5Ge epilayer is quantified as a100 = 0.5443 nm, a010 = 0.5429 nm and a001 = 0.5440 nm (all ± 0.0001 nm), and α = β = 90°, γ = 89.96 ± 0.02°. These local symmetry changes are most likely due to surface relaxation phenomena.

Structural characterization of laser ablated epitaxial (Ba0.5Sr0.5)TiO3 thin films on MgO(001) by synchrotron x-ray scattering

1999 ◽  
Vol 14 (7) ◽  
pp. 2905-2911 ◽  
Author(s):  
Sangsub Kim ◽  
Tae Soo Kang ◽  
Jung Ho Je
Keyword(s):  
Thin Films ◽  
Early Stage ◽  
Lattice Parameter ◽  
Normal Direction ◽  
X Ray ◽  
X Ray Scattering ◽  
Surface Normal ◽  
Out Of Plane ◽  
Axis Parallel ◽  
Ray Scattering

Epitaxial (Ba0.5Sr0.5) TiO3 thin films of two different thickness (∼25 and ∼134 nm) on MgO(001) prepared by a pulsed laser deposition method were studied by synchrotron x-ray scattering measurements. The film grew initially with a cube-on-cube relationship, maintaining it during further growth. As the film grew, the surface of the film became significantly rougher, but the interface between the film and the substrate did not. In the early stage of growth, the film was highly strained in a tetragonal structure (c/a = 1.04) with the longer axis parallel to the surface normal direction. As the growth proceeded further, it relaxed to a cubic structure with the lattice parameter near the bulk value, and the mosaic distribution improved significantly in both in- and out-of-plane directions. The thinner film (∼25 nm) showed only one domain limited mainly by the film thickness, but the thicker film (∼134 nm) exhibited three domains along the surface normal direction.

scholarly journals Influence of an MgTiTaON Inserted Layer on Magnetic Properties and Microstructure of FePtAgC Films

Coatings ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 238 ◽  
Author(s):  
Jai-Lin Tsai ◽  
Cheng Dai ◽  
Jyun-you Chen ◽  
Ting-Wei Hsu ◽  
Shi-Min Weng ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Cross Section ◽  
Lattice Relaxation ◽  
Fept Film ◽  
Perpendicular Magnetization ◽  
Aspect Ratios ◽  
Out Of Plane ◽  
Temperature Deposition ◽  
Critical Lattice ◽  
C 30

The FePt film above 10 nm critical lattice relaxation thickness was prepared and the ultrathin MgTiTaON layer was interleaved in between FePt film and the multilayer stack is FePt(6 nm)/[MgTiTaON(1 nm)/FePt(4 nm)]2. Next, the FePt films were co-sputtered with (Ag, C) segregants during deposition and the layer stacks is FePt(6 nm)(Ag, C)(x vol %)/[MgTiTaON (1 nm)/FePt(4 nm)(Ag, C) (x vol %)]2 (x = 0, 10, 20, 30, 40). After high temperature deposition at 470 °C, the granular FePt(Ag, C, MgTiTaON) film illustrated perpendicular magnetization and the out-of-plane coercivity (Hc) was increased with (Ag, C) segregants and the highest Hc is 18.3 kOe when x = 40. From cross-section images, the FePt layer are more continuous with 0 and 10 vol% (Ag, C) segregants and changed to an island structure when the (Ag, C) segregants increase to 20–40 vol %. The FePt grains were grown in separated islands in 20, 30 vol % (Ag, C) and changed to dense columnar-like morphology in 40 vol%. The second nucleated grains which contribute the in-plane magnetization are found in FePt (Ag, C) (40 vol %) film. The FePt islands are reached by inserting the ultrathin MgTiTaON layer and the island heights of FePt(Ag, C) (30, 40 vol %) are around 31–38 nm and the aspect ratios are 0.6–0.8.

Optical and microstructural properties of self-assembled InAs quantum structures in silicon

Open Physics ◽  
2011 ◽  
Vol 9 (2) ◽  
Author(s):  
Sławomir Prucnal ◽  
Marcin Turek ◽  
Andrzej Drozdziel ◽  
Krzysztof Pyszniak ◽  
Artur Wójtowicz ◽  
...  
Keyword(s):  
Light Emission ◽  
Stoichiometric Composition ◽  
Lattice Relaxation ◽  
Average Diameter ◽  
Lattice Parameter ◽  
Longitudinal Optical ◽  
Quantum Structures ◽  
Phonon Modes ◽  
Relaxation Energy ◽  
Oriented Parallel

AbstractThe InAs quantum structures were formed in silicon by sequential ion implantation and subsequent thermal annealing. Two kinds of crystalline InAs nanostructures were successfully synthesized: nanodots (NDs) and nanopyramids (NPs). The peaks at 215 and 235 cm−1, corresponding to the transverse optical (TO) and longitudinal optical (LO) InAs single-phonon modes, respectively, are clearly visible in the Raman spectra. Moreover, the PL band at around 1.3 µm, due to light emission from InAs NDs with an average diameter 7±2 nm, was observed. The InAs NPs were found only in samples annealed for 20 ms at temperatures ranging from 1000 up to 1200°C. The crystallinity and pyramidal shape of InAs quantum structures were confirmed by HRTEM and XRD techniques. The average size of the NPs is 50 nm base and 50 nm height, and they are oriented parallel to the Si (001) planes. The lattice parameter of the NPs increases from 6.051 to 6.055 Å with the annealing temperature increasing from 1100 to 1200°C, due to lattice relaxation. Energy dispersive spectroscopy (EDS) shows almost stoichiometric composition of the InAs NPs.

Critical Layer Thickness: Theory and Experiment in the ZnSe/GaAs (001) Material System

2017 ◽  
Vol 26 (03) ◽  
pp. 1740020
Author(s):  
Tedi Kujofsa ◽  
John E. Ayers
Keyword(s):  
Layer Thickness ◽  
Flow Model ◽  
Driving Forces ◽  
Lattice Relaxation ◽  
Theoretical Models ◽  
Critical Layer ◽  
Material System ◽  
Critical Layer Thickness ◽  
Experimental Resolution ◽  
Experimental Strain

The critical layer thickness (CLT) determines the criteria for dislocation formation and the onset of lattice relaxation. Although several theoretical models have been developed for the critical layer thickness, experimentally-measured CLTs in ZnSe/GaAs (001) heterostructures are often at variance with one another as well as with established theories. In a previous work [T. Kujofsa et al., J. Vac. Sci. Technol. B, 34, 051201 (2016)], we showed that the experimentally measured CLT may be much larger than the equilibrium value when using finite experimental resolution. In this work, we apply a general dislocation flow model to determine the apparent critical layer thickness as a function of the experimental resolution for ZnSe/GaAs (001) heterostructures. More importantly, we compare the results utilizing different equilibrium theories and therefore varying driving forces for the lattice relaxation in order to determine which established models are consistent with several measured values of CLT for ZnSe/GaAs (001) once kinetically-limited relaxation and finite experimental strain resolution are taken into account.

scholarly journals Synthesis, Characterization, and Thermal Decomposition of Pure and Dysprosium Doped Yttrium Phosphate System

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
K. K. Bamzai ◽  
Nidhi Kachroo ◽  
Vishal Singh ◽  
Seema Verma
Keyword(s):  
Thermogravimetric Analysis ◽  
Ammonium Hydroxide ◽  
Xrd Analysis ◽  
Lattice Parameter ◽  
Energy Dispersive ◽  
Water Molecules ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Structural Investigations ◽  
X Ray

Yttrium phosphate and dysprosium doped yttrium phosphate were synthesized from aqueous solutions using rare earth chloride, phosphoric acid, and traces of ammonium hydroxide. The synthesized material was then characterized for their structural investigations using powder X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) supplemented with energy dispersive X-ray analysis (EDAX). The spectroscopic investigations were carried out using Fourier transform infrared (FTIR) spectroscopy. The thermal stability was studied using differential thermogravimetric analysis (DTA), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) techniques. X-ray diffraction analysis reveals that both yttrium phosphate and dysprosium doped yttrium phosphate belong to tetragonal system with lattice parameter  Å,  Å and  Å,  Å, respectively. The stoichiometry of the grown composition was established by energy dispersive X-ray analysis. The EDAX analysis suggests the presence of water molecules. The presence of water molecules along with orthophosphate group and metallic ion group was confirmed by FTIR analysis. Thermogravimetric analysis suggests that decomposition in case of yttrium phosphate takes place in three different stages and the final product stabilizes after 706°C, whereas in case of dysprosium doped yttrium phosphate the decomposition occurs in two different stages, and the final product stabilizes after 519°C.

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