Compositional modulation in InxGa1−xN: TEM and X-ray studies

Microscopy ◽  
2005 ◽  
Vol 54 (3) ◽  
pp. 243-250 ◽  
Author(s):  
Zuzanna Liliental-Weber ◽  
Dmitri N. Zakharov ◽  
Kin M. Yu ◽  
Joel W. Ager ◽  
Wladyslaw Walukiewicz ◽  
...  
Keyword(s):  
X Ray ◽  
Compositional Modulation

Compositional Modulation and its Optoelectric Properties of Zn(S,Se,Te) Crystals Grown by Hydrogen Radical-Enhanced CVD

1995 ◽  
Vol 417 ◽  
Author(s):  
Hiroyuki Fujiwara ◽  
Toshihiro Ii ◽  
Isamu Shimizu
Keyword(s):  
Deep Level ◽  
Chemical Vapor ◽  
X Ray Diffraction ◽  
Small Shift ◽  
X Ray ◽  
Compositional Modulation ◽  
Peak Energy ◽  
Large Lattice ◽  
The Difference ◽  
Hydrogen Radical

AbstractHigh-quality (ZnS)n(ZnSe)12n and (ZnSe)n(ZnTe)11n (n=1∼4) crystals were grown at a low temperature of 200°C by hydrogen radical-enhanced chemical vapor deposition. From satellite peaks in x-ray diffraction spectra, these periodic structure crystals were confirmed to be grown coherently on substrates, in spite of large lattice mismatches between the grown layers and the substrates (͛=4∼7%). In photoluminescence (PL) spectra of these films, strong band-edge emissions were predominantly observed, resulting from a suppression of deep-level emissions. We found that the PL peak energy of (ZnSe)n(ZnTe)11n shifts systematically to lower energy by 200 meV with changes in the number of ZnSe layers (n), while relatively small shift of 13 meV was observed in (ZnS)n(ZnSe)12n. These discrepancy can be attributed to the difference of band-lineups or chemical natures of constituent atoms in these crystals.

Structural Studies of Sputtered Ni80Co20/Cu Multilayers

1995 ◽  
Vol 382 ◽  
Author(s):  
X. Bian ◽  
Z. Altounian ◽  
J. O. Ström-Olsen ◽  
M. Sutton ◽  
R. W. Cochrane
Keyword(s):  
Optical Model ◽  
Film Growth ◽  
Growth Direction ◽  
Interface Roughness ◽  
High Angle ◽  
X Ray ◽  
Compositional Modulation ◽  
Large Expansion ◽  
Reflectivity Data ◽  
Coherent Interfaces

ABSTRACTThe structure of magnetron-sputtered Ni80Co20/Cu multilayershas been investigated by low and high-angle X-ray diffractometry. Low-angle x-ray reflectivity data reveal well-defined compositional modulation along the film growth direction for a wide Cii thickness range of 5-40 Å. The data analysis, based on anl optical model, shows that interfacial mixing is limited to ∼3-4 Å As the number of bilayers increased from 8 to 100, the interface roughness increased by a factor of 3. Better layered structures were found for relatively thick Cu layers (tCu>10Å). The high-angle diffraction data were analyzed using a trapezoidal model. The results indicate that the films have a polycrystalline structure with a preferred (111)orientation with coherent interfaces of ∼ 100-240 Ådepending on the Cu layer thickness. The relatively large expansion of (111) spacings in NiCo alloy layers gives rise to the lower atomic ordering in NiCo/Cu multilayers.

Structural Studies and Magnetotransport Properties of Sputtered Ni/Co Multilayers

1995 ◽  
Vol 384 ◽  
Author(s):  
J.M. Freitag ◽  
X. Bian ◽  
Z. Altounian ◽  
J.O. Ström-Olsen ◽  
R.W. Cochrane
Keyword(s):  
Room Temperature ◽  
Film Growth ◽  
Growth Direction ◽  
Structural Studies ◽  
Dc Magnetron Sputtering ◽  
X Ray ◽  
Compositional Modulation ◽  
Small Fields ◽  
Structural Characterizations ◽  
Magnetoresistive Sensitivity

ABSTRACTFerromagnetic/ferromagnetic Ni/Co multilayers were prepared by DC-magnetron sputtering with component layer thicknesses ranging from 40 Å down to 5 Å. Structural characterizations by x-ray diffractometry show a well-defined compositional modulation along the film growth direction and a preferred (111) crystalline orientation. A longitudinal magnetoresistance ΔR/R over 2.7% with a sensitivity of ~0.11%/Oe was measured at room temperature in small fields less than 20 Oe. The highest room temperature sensitivity obtained in this system was 0.16%/Oe. Magnetoresistive sensitivity was found to vary inversely with the number of bilayers in the multilayers. The magnetic anisotropy of the films as determined by MOKE magnetometry is correlated to the magnetoresistance and indicative of an AMR effect.

X‐ray analysis of compositional modulation in Co/Pt multilayer films for magneto‐optic recording

1993 ◽  
Vol 74 (2) ◽  
pp. 996-1000 ◽  
Author(s):  
J. A. Bain ◽  
B. M. Clemens ◽  
H. Notarys ◽  
E. E. Marinero ◽  
S. Brennan
Keyword(s):  
Multilayer Films ◽  
X Ray ◽  
Compositional Modulation ◽  
Magneto Optic

Complex Superstructures Resulting from Compositional Modulation and Octahedral Tilt Twinning in AA′BB′O6 Doubly Cation Ordered Perovskites

2013 ◽  
Vol 2013 (CICMT) ◽  
pp. 000006-000013
Author(s):  
Graham King ◽  
Susana Garcia-Martin ◽  
Esteban Urones-Garrote ◽  
Gwilherm Nenert ◽  
Patrick M. Woodward
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Electron Diffraction ◽  
Neutron Powder Diffraction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Compositional Modulation ◽  
System A ◽  
Transmission Electron

The ordering of cations within the perovskite structure can have a profound effect on the physical properties. A number of AA′BB′O6 perovskite phases which have both a rock salt ordering of the B/B′ cations and a layered ordering of the A/A′ cations have recently been prepared and studied. In some of these compositions complex nanoscale superstructure formation has been observed. These superstructures are the result of compositional modulations involving the occupancies of the A and A′ cations and are accompanied by a twinning of the octahedral tilt system. A wide variety of patterns are observed, such as 1-dimensional stripes or 2-dimensional chessboards which can have periodicities which are either commensurate or incommensurate with the underlying subcell. These superstructures cannot be easily detected by powder X-ray diffraction but have been observed using a combination of high resolution transmission electron microscopy, electron diffraction, and neutron powder diffraction. The factors which determine the dimensionality and periodicity of the superstructures are discussed and compared with the closely related Li based perovskite systems.

X‐ray observation of compositional modulation caused by phase decomposition in GaInP ternary alloys

1990 ◽  
Vol 56 (4) ◽  
pp. 337-339 ◽  
Author(s):  
Hiroshi Okuda ◽  
Makoto Kondo ◽  
Kiyoko Kato ◽  
Kazuo Nakajima
Keyword(s):  
Ternary Alloys ◽  
Phase Decomposition ◽  
X Ray ◽  
Compositional Modulation

Effects of nitrogen flow rates on reactively sputtered nanocrystal-(Ti,Al)xN1-x/amorphous-SiyN1-y nanolaminate films

2004 ◽  
Vol 19 (8) ◽  
pp. 2322-2329 ◽  
Author(s):  
Bao-Shun Yau ◽  
Jow-Lay Huang ◽  
Ding-Fwu Lii
Keyword(s):  
Flow Rate ◽  
Target Surface ◽  
Nitrogen Flow ◽  
Nitrogen Flow Rate ◽  
Flow Rates ◽  
X Ray ◽  
Nanocrystallite Size ◽  
Compositional Modulation ◽  
Atomic Force ◽  
Transmission Electron

Nanocrystal-(Ti,Al)xN1-x/amorphous-SiyN1-y nanolaminate films were deposited periodically under different nitrogen flow rates. The composition, microstructure and mechanical properties of nanolaminate films were investigated by x-ray photoelectron spectroscope, x-ray diffractometer, scanning and transmission electron microscopy, atomic force microscope, and nanoindentation apparatus. Results indicated that the formation of the compound on the target surface was substantially influenced by the deposition rate, composition and crystallite size of the nanolaminate films. Nanolaminate structure with periodic compositional modulation and sharp interfaces were deposited at different nitrogen flow rate. Smaller nanocrystallite size, round-shaped grain features, smoother surface morphology, higher hardness, and reduced elastic modulus were obtained for nanolaminate films with increasing the nitrogen flow rate.

Interdiffusion in Coherent Si0.90Ge0.10/Si0.95Ge0.05 Superlattices

2003 ◽  
Vol 795 ◽  
Author(s):  
D. B. Aubertine ◽  
P. C. McIntyre
Keyword(s):  
Concentration Dependence ◽  
Activation Enthalpy ◽  
High Sensitivity ◽  
Epitaxial Thin Films ◽  
X Ray Diffraction ◽  
Strained Si ◽  
X Ray ◽  
Compositional Modulation ◽  
X Ray Scattering ◽  
Ray Scattering

ABSTRACTWe present the use of x-ray scattering from Si1-XGeX/Si1-YGeY superlattices as a tool for measuring the concentration dependence of interdiffusivity in Si/SiGe epitaxial thin films. Although x-ray scattering from compositionally modulated films is an ultra-high-sensitivity technique for measuring interdiffusion in a variety of systems, the concentration dependence of Si/SiGe interdiffusion complicates its interpretation. We show that these complications can be avoided using Si1-XGeX/Si1-YGeY superlattices with a small compositional modulation. This strategy is assessed using numerical simulations of both interdiffusion and dynamical x-ray diffraction. We demonstrate its effectiveness by measuring the activation enthalpy and exponential prefactor for interdiffusion in compressively strained Si0.925Ge0.075. The results are 4.38 ± 0.05 eV and 36 ± 9 cm2/s respectively.

Microstructure and Magnetic Behavior of Fe/Ti Multilayered Films

1988 ◽  
Vol 132 ◽  
Author(s):  
Satoshi Ono ◽  
Michio Nitta ◽  
Masahiko Naoe
Keyword(s):  
Saturation Magnetization ◽  
Magnetic Behavior ◽  
X Ray Diffraction ◽  
Diffraction Intensity ◽  
Multilayered Films ◽  
X Ray ◽  
Compositional Modulation ◽  
Periodic Microstructure ◽  
Ar Gas ◽  
Bcc Phase

ABSTRACTFe/Ti multilayered films composed of Fe and Ti layers with various thickness ( dFe of 10 ∼ 1000 A and dTi of 10 ∼ 200 A ) have been prepared at Ar gas pressure of 2 mTorr by two pairs of Facing Targets Sputtering apparatus which can deposit very thin and continuous films on plasma-free substrates. The total thickness of Fe layers was 1000 A in all of the specimen films.The periodic microstructure due to compositional modulation was clearly observed not only in the low angle region of X-ray diffraction diagrams but also in the Auger electron spectroscopic depth profile.With decreasing dFe from 1000 to 20 A, the diffraction intensity of (110) plane in the Fe bcc phase lowered for dTi of 10∼200 A and its interplanar spacing ( d-spacing ) increased for dTi above 50A. This diffraction peak disappeared with further decreasing d below 15 A. At dFe around 25 A, a different peak appeared at the angle slightly lower than that of Fe(110) peak. The diffraction intensity of (002) plane in the Ti hcp phase increased with decreasing dFe. However, its d-spacing depended little on the dFe and took the same value as that of bulk Ti except for very small dTi.The net saturation magnetization of Fe layers in all of the specimen films decreased gradually with decreasing dFe from 1000 to 50 A, decreased abruptly with further decreasing dFe and became nearly zero at dFe below 15A.The films annealed at 200 and 400 °C showed obscure periodic microstructure and had larger d-spacing of ∝ −Fe(110) and smaller saturation magnetization than those of the as-deposited ones.

Space and Time Distribution of Hard X-Ray Emission in a Loop at the Beginning of a Flare

1994 ◽  
Vol 144 ◽  
pp. 275-277
Author(s):  
M. Karlický ◽  
J. C. Hénoux
Keyword(s):  
Time Distribution ◽  
Electron Bombardment ◽  
Spatial Evolution ◽  
Superthermal Electrons ◽  
Flare Loop ◽  
X Ray ◽  
Superthermal Electron ◽  
Flare Loops ◽  
Chromospheric Evaporation ◽  
Temporal And Spatial

AbstractUsing a new ID hybrid model of the electron bombardment in flare loops, we study not only the evolution of densities, plasma velocities and temperatures in the loop, but also the temporal and spatial evolution of hard X-ray emission. In the present paper a continuous bombardment by electrons isotropically accelerated at the top of flare loop with a power-law injection distribution function is considered. The computations include the effects of the return-current that reduces significantly the depth of the chromospheric layer which is evaporated. The present modelling is made with superthermal electron parameters corresponding to the classical resistivity regime for an input energy flux of superthermal electrons of 109erg cm−2s−1. It was found that due to the electron bombardment the two chromospheric evaporation waves are generated at both feet of the loop and they propagate up to the top, where they collide and cause temporary density and hard X-ray enhancements.

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