Epitaxy of Single Crystal Phase Change Materials on Si(111)

2011 ◽  
Vol 1338 ◽  
Author(s):  
P. Rodenbach ◽  
K. Perumal ◽  
F. Katmis ◽  
W. Braun ◽  
R. Calarco ◽  
...  
Keyword(s):  
Phase Change ◽  
Molecular Beam ◽  
Phase Change Materials ◽  
Lattice Mismatch ◽  
X Ray Diffraction ◽  
Quadrupole Mass ◽  
Cubic Symmetry ◽  
X Ray ◽  
Si Substrates

ABSTRACTPhase change materials along the GeTe-Sb2Te3 pseudobinary line (GST) are grown by molecular beam epitaxy (MBE) on Si(111). The growth on (111) oriented substrates leads to greatly increased crystal quality compared to (001) oriented substrates, even for a high lattice mismatch. This holds true even for Si substrates which have a lattice mismatch of around 10% with respect to GST. The growth is controlled in situ via line of sight quadrupole mass spectrometer (QMS). Structural characterization is performed in situ by X-ray diffraction (XRD), which reveals a clear cubic symmetry of the film and a lattice slightly rhombohedrally distorted along the [111] direction.

Optical and structural prorerties of InAs epilayer on graded InGaAs

2001 ◽  
Vol 696 ◽  
Author(s):  
Gu Hyun Kim ◽  
Jung Bum Choi ◽  
Joo In Lee ◽  
Se-Kyung Kang ◽  
Seung Il Ban ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Residual Strain ◽  
Molecular Beam ◽  
Lattice Mismatch ◽  
Peak Position ◽  
Excitation Intensity ◽  
Total Thickness ◽  
Ingaas Layer ◽  
X Ray Diffraction ◽  
X Ray

AbstractWe have studied infrared photoluminescence (PL) and x-ray diffraction (XRD) of 400 nm and 1500 nm thick InAs epilayers on GaAs, and 4 nm thick InAs on graded InGaAs layer with total thickness of 300 nm grown by molecular beam epitaxy. The PL peak positions of 400 nm, 1500 nm and 4 nm InAs epilayer measured at 10 K are blue-shifted from that of InAs bulk by 6.5, 4.5, and 6 meV, respectively, which can be largely explained by the residual strain in the epilayer. The residual strain caused by the lattice mismatch between InAs and GaAs or graded InGaAs/GaAs was observed from XRD measurements. While the PL peak position of 400 nm thick InAs layer is linearly shifted toward higher energy with increase in excitation intensity ranging from 10 to 140 mW, those of 4 nm InAs epilayer on InGaAs and 1500 nm InAs layer on GaAs is gradually blue-shifted and then, saturated above a power of 75 mW. These results suggest that adopting a graded InGaAs layer between InAs and GaAs can efficiently reduce the strain due to lattice mismatch in the structure of InAs/GaAs.

A Study on the Growth of Cubic GaN Films Using an AlGaAs Buffer Layer Grown on GaAs (100) by Plasma-Assisted Molecular Beam Epitaxy

2000 ◽  
Vol 639 ◽  
Author(s):  
Ryuhei Kimura ◽  
Kiyoshi Takahashi ◽  
H. T. Grahn
Keyword(s):  
Molecular Beam Epitaxy ◽  
Buffer Layer ◽  
Molecular Beam ◽  
High Energy ◽  
Rf Plasma ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cubic Gan

ABSTRACTAn investigation of the growth mechanism for RF-plasma assisted molecular beam epitaxy of cubic GaN films using a nitrided AlGaAs buffer layer was carried out by in-situ reflection high energy electron diffraction (RHEED) and high resolution X-ray diffraction (HRXRD). It was found that hexagonal GaN nuclei grow on (1, 1, 1) facets during nitridation of the AlGaAs buffer layer, but a highly pure, cubic-phase GaN epilayer was grown on the nitrided AlGaAs buffer layer.

Bi-Based Superconducting Multilayers Obtained by Molecular Beam Epitaxy

1999 ◽  
Vol 13 (09n10) ◽  
pp. 991-996
Author(s):  
M. Salvato ◽  
C. Attanasio ◽  
G. Carbone ◽  
T. Di Luccio ◽  
S. L. Prischepa ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Xrd Analysis ◽  
High Energy ◽  
X Ray Diffraction ◽  
One Dimensional ◽  
X Ray ◽  
Diffraction Model ◽  
Different Thickness

High temperature superconducting multilayers have been obtained depositing Bi2Sr2CuO6+δ(2201) and ACuO2 layers, where A is Ca or Sr, by Molecular Beam Epitaxy (MBE) on MgO and SrTiO3 substrates. The samples, formed by a sequence of 2201/ACuO2 bilayers, have different thickness of ACuO2 layers while the thickness of the 2201 layers is kept constant. The surface structure of each layer has been monitored by in situ Reflection High Energy Electron Diffraction (RHEED) analysis which has confirmed a 2D nucleation growth. X-ray diffraction (XRD) analysis has been used to confirm that the layered structure has been obtained. Moreover, one-dimensional X-ray kinematic diffraction model has been developed to interpret the experimental data and to estimate the period of the multilayers. Resistive measurements have shown that the electrical properties of the samples strongly depend on the thickness of the ACuO2 layers.

PROPERTIES OF MBE-GROWN SUPERLATTICES AND ULTRA-THIN FILMS

1993 ◽  
Vol 07 (01n03) ◽  
pp. 446-451
Author(s):  
CHARLES M. FALCO ◽  
BRAD N. ENGEL
Keyword(s):  
Lattice Spacing ◽  
Molecular Beam ◽  
Magnetic Transition ◽  
Magnetic Behavior ◽  
Atomic Layer ◽  
High Symmetry ◽  
X Ray Diffraction ◽  
X Ray ◽  
Layer 2

We have used Molecular Beam Epitaxy (MBE) to grow single-crystal Co/Pd superlattices and Co/TM (TM=Cu, Pd, Ag) bilayers and sandwiches along the three high-symmetry crystal directions; [001], [110], and [111]. In the case of Co/Pd superlattices, we previously reported from x-ray diffraction measurements that for small Co thicknesses the (001) oriented superlattices are coherently strained in-plane to near the bulk Pd lattice spacing. This strain leads to a very large in-plane magnetoelastic volume anisotropy for these superlattices. Here we report quantitative in situ RHEED measurements of Co deposited on Pd (001) that confirm this coherently strained growth. We have also used in situ polar Kerr ellipticity measurements to study the perpendicular magnetic behavior of Pd/Co/TM (111) sandwich structures, where TM is the non-magnetic transition metal overlayer Ag, Cu or Pd. We observed perpendicular loops with coercive fields of H c ≤ 200 Oe for the uncovered Co films for t co ≤ 6 Å, becoming in-plane above this thickness. However, subsequent deposition of just one atomic layer (≈ 2 Å) of any of the TM over the Co resulted in strongly perpendicular, square hysteresis curves with H c ≥ 900 Oe for all films in the Co thickness range studied.

Residual Stresses in Sputtered ZnO Films on (100) Si Substrates by XRD

2009 ◽  
Vol 1201 ◽  
Author(s):  
Florine Conchon ◽  
Pierre-Olivier Renault ◽  
Philippe Goudeau ◽  
Eric Le Bourhis ◽  
Elin Sondergard ◽  
...  
Keyword(s):  
Residual Stresses ◽  
Annealing Temperature ◽  
Protective Coatings ◽  
Zno Films ◽  
X Ray Diffraction ◽  
X Ray ◽  
Si Substrates ◽  
Thermally Activated ◽  
Post Deposition

AbstractResidual stresses in sputtered ZnO films on Si are investigated and discussed. By means of X-ray diffraction, we show that as-deposited ZnO films encapsulated or not by Si3N4 protective coatings are highly compressively stressed. Moreover, a transition of stress is observed as a function of the post-deposition annealing temperature. After a heat treatment at 800°C, ZnO films are tensily stressed while ZnO films encapsulated by Si3N4 are stress-free. With the aid of in-situ X-ray diffraction, we argue that this thermally-activated stress relaxation can be attributed to a variation of the chemical composition of the ZnO films.

Crystallization Characteristics of Ge-Sb Phase Change Materials

2009 ◽  
Vol 1160 ◽  
Author(s):  
Simone Raoux ◽  
Cyril Cabral ◽  
Lia Krusin-Elbaum ◽  
Jean L. Jordan-Sweet ◽  
Martin Salinga ◽  
...  
Keyword(s):  
Phase Change ◽  
Phase Change Materials ◽  
Mass Density ◽  
Large Change ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Time Resolved ◽  
X Ray ◽  
Diffraction Peaks ◽  
Low X

AbstractThe crystallization behavior of Ge-Sb phase change materials with variable Ge:Sb ratio X between 0.079 and 4.3 was studied using time-resolved x-ray diffraction, differential scanning calorimetry, x-ray reflectivity, optical reflectivity and resistivity vs. temperature measurements. It was found that the crystallization temperature increases with Ge content from about 130 °C for X = 0.079 to about 450 °C for X = 4.3. For low X, Sb x-ray diffraction peaks occurred during a heating ramp at lower temperature than Ge diffraction peaks. For X = 1.44 and higher, Sb and Ge peaks occurred at the same temperature. Mass density change upon crystallization and optical and electrical contrast between the phases show a maximum for the eutectic alloy with X = 0.17. The large change in materials properties with composition allows tailoring of the crystallization properties for specific application requirements.

Recovery kinetics of the GaAs(001) surface in molecular beam epitaxy studied by in situ X-ray diffraction

2005 ◽  
Vol 357 (1-2) ◽  
pp. 165-169 ◽  
Author(s):  
Vladimir M. Kaganer ◽  
Wolfgang Braun ◽  
Bernd Jenichen ◽  
Klaus H. Ploog
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
X Ray Diffraction ◽  
X Ray ◽  
Kinetics Of

Thermal Residual Stress Relaxation in Sputtered ZnO Film on (100) Si Substrate Studied In Situ by Synchrotron X-Ray Diffraction

2011 ◽  
Vol 681 ◽  
pp. 127-132
Author(s):  
Christopher Krauss ◽  
Guillaume Geandier ◽  
Florine Conchon ◽  
Pierre Olivier Renault ◽  
Eric Le Bourhis ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stress Relaxation ◽  
Structural Changes ◽  
Zno Films ◽  
X Ray Diffraction ◽  
X Ray ◽  
Si Substrates ◽  
Compressive Stresses ◽  
Residual Stress Relaxation

Residual stress relaxation in sputtered ZnO films has been studied in-situ by synchrotron x-ray diffraction. The films deposited on (001) Si substrates were thermally treated from 25°C to 700°C. X-ray diffraction 2D patterns were captured continuously during the heating, plateau and cooling ramps. The corrections carried out for compensating the furnace drift are discussed. We first observe an increase of the intrinsic compressive stresses before stress relaxation starts to operate around 370°C. Then, thermal contraction upon cooling dominates so that overall, the large initial compressive film stresses turn to tensile after thermal treatment. The overall behaviour is discussed in terms of structural changes induced by the heat treatment.

Fe3O4/MgO Superlattices Grown on MgO(OOl) and Fe/MgO(001) by Molecular Beam Epitaxy

1997 ◽  
Vol 474 ◽  
Author(s):  
G. Chern ◽  
C. L. Chang ◽  
Y. R. Chean
Keyword(s):  
Molecular Beam ◽  
Lattice Mismatch ◽  
High Energy ◽  
High Energy Electron ◽  
X Ray Diffraction ◽  
Oxide Interface ◽  
High Crystalline Quality ◽  
X Ray ◽  
Coated Surface

AbstractThe growth and structural characterization of Fe3O4/MgO superlattices on MgO(001) and Fe-coated MgO(001) are compared. Long modulated coherence and sharp interface are revealed by X-ray diffraction and reflection high energy electron diffraction (RHEED). For the superlattice grown directly on MgO(001), high crystalline quality is comparable to the previous report on the oxide superlattice system. For the superlattice grown on Fe/MgO(001), both chemical and lattice spacing modulations are maintained which is different from the polycrystlline structure of the Fe3O4/NiO grown on Ni-based system. This superiority of the growth on Fe-coated surface results from both the smaller lattice mismatch and the oxidation state of Fe relative to MgO. The changes of the RHEED intensity during the growth of these superlattices are also measured. The evolution of the oxide interface during the growth of Fe3O4/MgO is quantitatively presented.

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