MBE Growth and Characterization of CdTe, ZnTe Epilayers and CdTe/ZnCdTe Superlattices on GaAs Substrates

1992 ◽  
Vol 263 ◽  
Author(s):  
A.E. Milokhin ◽  
I.E. Trofimov ◽  
M.V. Petrov ◽  
F.F. Balakirev ◽  
V.D. Kuzmin ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Buffer Layer ◽  
Lattice Constant ◽  
Strong Influence ◽  
High Crystalline Quality ◽  
Mbe Growth ◽  
X Ray ◽  
Gaas Substrates

Semiconductor heterostuctures ZnxCd1−xTe/CdTe were found to be of interest recently due to their potential practical usage. The reason for this is the beautiful variety of electrical heterostucture properties which arise from the strong influence of elastic deformation distribution. Thin epilayer films and superlattices ZnxCd1−xTe/CdTe were prepared on GaAs semi-isolator substrates by MBE technology with RHEED oscillation measurements of the deposited layers. X-ray measurements have shown high crystalline quality of the samples.We have performed Raman scattering studies of ZnxZnxCd1−xTe/CdTe structures. The data obtained were interpreted as a proff of the pseudomorphous growth model. That is, ZnxCd1−xTe/CdTe SLS keeps the lattice constant of the buffer layer.

Mbe Growth and Characterization of (GaAs)l−x(Si2)x and (GaAs)1−x(Si2)x/GaAs Superlattices on GaAs Substrates

1995 ◽  
Vol 379 ◽  
Author(s):  
H.P. Lee ◽  
F.J. Szalkowski ◽  
X. Zeng ◽  
J. Wolfenstine ◽  
J. W. Ager
Keyword(s):  
Molecular Beam ◽  
Stacking Faults ◽  
Cross Sectional ◽  
Mbe Growth ◽  
X Ray ◽  
Gaas Substrates ◽  
Transmission Electron ◽  
Evaporation Source ◽  
Scattering Measurement

ABSTRACTLateral compositional graded (GaAs)1-x(Si2)x alloys were deposited on GaAs substrates in a III-V molecular beam epitaxy (MBE) chamber equipped with a electron-beam Si evaporation source. Single crystal GaAs-Si alloys were formed when the deposition temperature was 600°C or higher. The alloys were characterized by Energy Dispersive X-ray Spectroscopy (EDS), Raman scattering measurement and cross-sectional Transmission Electron Microscopy (XTEM). Dislocation-free (GaAs)1-x(Si2)x films of up to x = 0.07 were deposited. For alloys with x between 0.15 < < 0.25, the morphology deteriorates and a high density of stacking faults and micro-twins were observed.

MBE Growth and Characterization of InSb/AlxIn1−xSb Strained Layer Structures

1996 ◽  
Vol 450 ◽  
Author(s):  
K. J. Goldammer ◽  
W. K. Liu ◽  
W. Ma ◽  
M. B. Santos ◽  
R. J. Hauenstein ◽  
...  
Keyword(s):  
Quantum Wells ◽  
High Mobility ◽  
Structural Quality ◽  
Electron Systems ◽  
X Ray Diffraction ◽  
Mbe Growth ◽  
Gaas Substrates ◽  
Layer Structures

ABSTRACTThree types of structures were fabricated using molecular beam epitaxy. High-resolution x-ray diffraction measurements demonstrated the high structural quality of InSb/AlxIn1−xSb superlattices grown on InSb and GaAs substrates. Hall effect data revealed the effect of substrate temperature on autocompensation in InSb δ-doped with Si. Two-dimensional electron systems with a high mobility were realized in InSb quantum wells with AlxIn1−xSb barriers δ-doped with Si.

Characterization of Natural and Synthesized FeTiO3 Crystals With RBS/PIXE/XRD

1997 ◽  
Vol 07 (03n04) ◽  
pp. 265-275
Author(s):  
R. Q. Zhang ◽  
S. Yamamoto ◽  
Z. N. Dai ◽  
K. Narumi ◽  
A. Miyashita ◽  
...  
Keyword(s):  
Single Crystals ◽  
Ion Beam ◽  
Pressure Control ◽  
Floating Zone ◽  
X Ray Diffraction ◽  
X Ray ◽  
Beam Analysis ◽  
Ppm Level

Natural FeTiO 3 (illuminate) and synthesized FeTiO 3, single crystals were characterized by Rutherford backscattering spectroscopy combined with channeling technique and particle-induced x-ray emission (RBS-C and PIXE). The results obtained by the ion beam analysis were supplemented by the x-ray diffraction analysis to identify the crystallographic phase. Oriented single crystals of synthesized FeTiO 3 were grown under the pressure control of CO 2 and H 2 mixture gas using a single-crystal floating zone technique. The crystal quality of synthesized FeTiO 3 single crystals could be improved by the thermal treatment but the exact pressure control is needed to avoid the precipitation of Fe 2 O 3 even during the annealing procedure. Natural FeTiO 3 contains several kinds of impurities such as Mn , Mg , Na and Si . The synthesized samples contain Al , Si and Na which are around 100 ppm level as impurities. The PBS-C results of the natural sample imply that Mn impurities occupy the Fe sublattice in FeTiO 3 or in mixed phase between ilmenite and hematite.

Magnetic Anisotropy in Electrodeposited CO Films and spin-valves on Gaas Substrates

1999 ◽  
Vol 562 ◽  
Author(s):  
K. Attenborough ◽  
M. Cerisier ◽  
H. Boeve ◽  
J. De Boeck ◽  
G. Borghs ◽  
...  
Keyword(s):  
Magnetic Anisotropy ◽  
Buffer Layer ◽  
Structural Properties ◽  
Easy Axis ◽  
Spin Valve ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cu Films ◽  
Gaas Substrates ◽  
Unique Spin

ABSTRACTWe have studied the magnetic and structural properties of thin electrodeposited Co and Cu layers grown directly onto (100) n-GaAs and have investigated the influence of a buffer layer. A dominant fourfold anisotropy with a uniaxial contribution is observed in 10 nm Co electrodeposited films on GaAs. An easy axis is observed in the [001] GaAs direction with two hard axes of differing coercivities parallel to the [011] and [011] directions. For thicker films the easy axes in the [001] direction becomes less pronounced and the fourfold anisotropy becomes less dominant. Co films of similar thicknesses deposited onto an electrodeposited Cu buffer layer were nearly isotropic. From X-ray diffraction 21 nm Co layers on GaAs were found to be hcp with the c-axis tending to be in the plane of the film. The anisotropy is ascribed to the Co/GaAs interface and is held responsible for the unique spin-valve properties seen recently in electrodeposited Co/Cu films.

Characterization of WC-Co Coatings Using HP/HVOF Process

1996 ◽  
Author(s):  
S.Y. Hwang ◽  
B.G. Seong ◽  
M.C. Kim
Keyword(s):  
Wear Resistance ◽  
X Ray Diffraction ◽  
High Carbon ◽  
Properties Of Coatings ◽  
X Ray ◽  
Hvof Process ◽  
Number Of Passes ◽  
Oxygen Fuel

Abstract To maintain surface roughness of process rolls in cold rolling steel plants, WC-Co coatings have been known to be effective ones. In this study, a high pressure/high velocity oxygen fuel (HP/HVOF) process was used to obtain WC-Co coatings. To get the best quality of coatings, WC-Co coatings are sprayed with numerous powders made by various processes. These powders include agglomerated sintered powders, fused-crushed powders, extra high carbon WC-Co powders and (W2C, WC)-Co powders. After spraying, properties of coatings such as hardness, wear resistance. X-ray diffraction, and microstructures were analyzed. For coatings produced by agglomerated-sintered powders, hardness of the coating increased as power levels and the number of passes were increased. In case of the coatings produced by fused-crushed powders, a very low deposition rate was obtained due to a low flowablity of the powders. In addition, the WC-Co coatings sprayed with extra carbon content of WC-Co did not show improved hardness and wear resistance. Also, some decomposition of WC was observed in the coating. Finally, the coatings produced by (W2C, WC)-Co powders produced higher hardness and lower wear resistance coating.

scholarly journals Crystallization, optimization and preliminary X-ray characterization of a metal-dependent PI-PLC fromStreptomyces antibioticus

2012 ◽  
Vol 68 (11) ◽  
pp. 1378-1386 ◽  
Author(s):  
Michael R. Jackson ◽  
Thomas L. Selby
Keyword(s):  
X Ray Diffraction ◽  
Hanging Drop ◽  
Orthorhombic Space Group ◽  
X Ray ◽  
Streptomyces Antibioticus ◽  
Cell Parameters ◽  
Heavy Atoms ◽  
Hanging Drop Method

A recombinant metal-dependent phosphatidylinositol-specific phospholipase C (PI-PLC) fromStreptomyces antibioticushas been crystallized by the hanging-drop method with and without heavy metals. The native crystals belonged to the orthorhombic space groupP222, with unit-cell parametersa= 41.26,b= 51.86,c = 154.78 Å. The X-ray diffraction results showed significant differences in the crystal quality of samples soaked with heavy atoms. Additionally, drop pinning, which increases the surface area of the drops, was also used to improve crystal growth and quality. The combination of heavy-metal soaks and drop pinning was found to be critical for producing high-quality crystals that diffracted to 1.23 Å resolution.

scholarly journals Regeneration of Planarian Auricles and Reestablishment of Chemotactic Ability

2021 ◽  
Vol 9 ◽  
Author(s):  
Eugene Matthew P. Almazan ◽  
Joseph F. Ryan ◽  
Labib Rouhana
Keyword(s):  
Molecular Mechanisms ◽  
Behavioral Experiments ◽  
X Ray ◽  
Preferential Expression ◽  
Chemical Stimuli ◽  
And Function ◽  
Function Models ◽  
Chemotactic Ability

Detection of chemical stimuli is crucial for living systems and also contributes to quality of life in humans. Since loss of olfaction becomes more prevalent with aging, longer life expectancies have fueled interest in understanding the molecular mechanisms behind the development and maintenance of chemical sensing. Planarian flatworms possess an unsurpassed ability for stem cell-driven regeneration that allows them to restore any damaged or removed part of their bodies. This includes anteriorly-positioned lateral flaps known as auricles, which have long been thought to play a central role in chemotaxis. The contribution of auricles to the detection of positive chemical stimuli was tested in this study using Girardia dorotocephala, a North American planarian species known for its morphologically prominent auricles. Behavioral experiments staged under laboratory conditions revealed that removal of auricles by amputation leads to a significant decrease in the ability of planarians to find food. However, full chemotactic capacity is observed as early as 2 days post-amputation, which is days prior from restoration of auricle morphology, but correlative with accumulation of ciliated cells in the position of auricle regeneration. Planarians subjected to x-ray irradiation prior to auricle amputation were unable to restore auricle morphology, but were still able to restore chemotactic capacity. These results indicate that although regeneration of auricle morphology requires stem cells, some restoration of chemotactic ability can still be achieved in the absence of normal auricle morphology, corroborating with the initial observation that chemotactic success is reestablished 2-days post-amputation in our assays. Transcriptome profiles of excised auricles were obtained to facilitate molecular characterization of these structures, as well as the identification of genes that contribute to chemotaxis and auricle development. A significant overlap was found between genes with preferential expression in auricles of G. dorotocephala and genes with reduced expression upon SoxB1 knockdown in Schmidtea mediterranea, suggesting that SoxB1 has a conserved role in regulating auricle development and function. Models that distinguish between possible contributions to chemotactic behavior obtained from cellular composition, as compared to anatomical morphology of the auricles, are discussed.

Thermal Treatment Induced Dislocation Bundles in Gaas Substrates Studied by Scanning Infrared Polariscopy, Visible-Light Interferometry, Transmission Electron Microscopy, Makyoh and X-Ray Topography

2000 ◽  
Vol 6 (S2) ◽  
pp. 1104-1105
Author(s):  
P. Mock
Keyword(s):  
Plastic Deformation ◽  
Technical Problem ◽  
Sample Holder ◽  
Mbe Growth ◽  
X Ray ◽  
Gaas Substrates ◽  
Transmission Electron ◽  
Topographic Survey ◽  
Key Factor ◽  
Peripheral Areas

It is well known that heat treatment induced plastic deformation of GaAs substrates is a key factor that reduces the yield of electronic devices in manufacturing processes on an industrial scale. Our recent X-ray topographic survey showed that a quite common, radiatively heated, non In-bonded sample holder design can cause severe plastic deformation in two-inch diameter GaAs (001) substrates when they are heated up to about 650 °C in a molecular beam epitaxy (MBE) growth chamber. Unintentional plastic deformation occurred for all three investigated MBE machines, which were of different make, but we overcame the technical problem by modifications to the sample holder of a user built MBE machine. At present, however, there is no theoretical model available that can satisfactorily describe the experimental observations including the spatial distribution of the majority of the dislocation bundles.The plastic deformation up to about 98 % is realised by bundles of dislocations which start at the sample edges around the four <100> peripheral areas,

Characterization and Granulometric Correction Soil for the Production of Soil-Cement Blocks for Two Method, Particle Size and X-Ray Florescence to be Inserted in Phase Change Materials (PCMS)

2014 ◽  
Vol 798-799 ◽  
pp. 355-359 ◽  
Author(s):  
Valter Bezerra Dantas ◽  
U.U. Gomes ◽  
A.B. Vital ◽  
G.S. Marinho ◽  
Ariadne de Souza Silva
Keyword(s):  
Particle Size ◽  
Phase Change Materials ◽  
Clay Content ◽  
Particle Size Analysis ◽  
Liquid Limit ◽  
Size Analysis ◽  
X Ray ◽  
Soil Cement

This paper presents the results of tests for characterization of soil samples collected in Mossoró-RN, UFERSA-RN Campus (5 ° 12'34 .68 "South latitude, 37 ° 19 '5.74 "west longitude), for the purpose of producing soil-cement for the manufacture of pressed blocks. Objective of improving the quality of soil-cement, and provide conditions for the use of the soil making it ideal for the production of soil-cement block. Tests of compaction, particle size analysis, plastic limit, liquid limit and correct particle size, X-ray fluorescence and morphology by scanning electron microscopy (SEM). It was concluded that the soil needs correction particle size, due to the high clay content. The method combined grading, sieving, sedimentation and blooming X-ray as the fastest and most accurate in correcting soil particle size.

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