New Approach to Growth of High-Quality GaAs Layers on Si Substrates

1988 ◽  
Vol 116 ◽  
Author(s):  
Jukka Varrio ◽  
Arto Salokatve ◽  
Harry Asonen ◽  
Minna Hovinen ◽  
Markus Pessa ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Layer Growth ◽  
Rutherford Backscattering ◽  
X Ray Diffraction ◽  
New Approach ◽  
Si Substrates ◽  
Surface Steps ◽  
Transmission Electron ◽  
Migration Enhanced Epitaxy ◽  
And Migration

AbstractGaAs layers were grown on Si (001) substrates by molecular beam epitaxy (MBE) and migration enhanced epitaxy (MEE). They were examined by transmission electron microscopy, doublecrystal X-ray diffraction and Rutherford backscattering/channeling technique. Initial layer growth in both MEE and MBE was governed by three-dimensional nucleation but a stronger tendency for GaAs islands to align along the surface steps of Si was observed in the case of MEE. There was no measurable tilt between the (001) planes of GaAs and Si if growth was initiated by MEE at low temperature, prior to further growth by MBE at higher temperatures. On the contrary, the tilt angle was 0.34• when the entire structure was prepared by conventional two-step MBE. Rutherford backscattering measurements indicated a significant reduction in the density of defects throughout MEE/MBE GaAs in comparison with MBE GaAs.

Generation and Suppression of Stacking Faults in Gap Layers Grown on Si(100) Substrates by Molecular Beam Epitaxy and Migration Enhanced Epitaxy

1996 ◽  
Vol 441 ◽  
Author(s):  
Y. Takagi ◽  
H. Yonezu ◽  
K. Samonji ◽  
T. Tsuji ◽  
N. Ohshima
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Stacking Faults ◽  
Misfit Dislocations ◽  
Generation Process ◽  
Si Substrates ◽  
Transmission Electron ◽  
Migration Enhanced Epitaxy ◽  
Regular Network ◽  
And Migration

AbstractWe have investigated the generation process of crystalline defects in GaP layers grown on Si substrates (GaP/Si) by molecular beam epitaxy (MBE) and migration enhanced epitaxy (MEE). Transmission electron microscopy observations revealed that a regular network of misfit dislocations was generated in GaP/Si by MEE. On the other hand, threading dislocations as well as interfacial misfit dislocations were observed in GaP/Si by MBE. Moreover, stacking faults were generated in high density at the hetero-interface of GaP/Si by MBE. The density of stacking faults was drastically reduced by MEE.

scholarly journals Synthesis of Three-Dimensional Fe3O4/Graphene Aerogels for the Removal of Arsenic Ions from Water

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Yan Ye ◽  
Da Yin ◽  
Bin Wang ◽  
Qingwen Zhang
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
3D Structure ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
X Ray ◽  
Graphene Aerogels ◽  
Transmission Electron ◽  
Potential Applications ◽  
Removal Of Arsenic

We report the synthesis of three-dimensional Fe3O4/graphene aerogels (GAs) and their application for the removal of arsenic (As) ions from water. The morphology and properties of Fe3O4/GAs have been characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and superconducting quantum inference device. The 3D nanostructure shows that iron oxide nanoparticles are decorated on graphene with an interconnected network structure. It is found that Fe3O4/GAs own a capacity of As(V) ions adsorption up to 40.048 mg/g due to their remarkable 3D structure and existence of magnetic Fe3O4nanoparticles for separation. The adsorption isotherm matches well with the Langmuir model and kinetic analysis suggests that the adsorption process is pseudo-second-ordered. In addition to the excellent adsorption capability, Fe3O4/GAs can be easily and effectively separated from water, indicating potential applications in water treatment.

scholarly journals Conformal Coating by Liquid Route on Three-Dimensional Topology

2018 ◽  
Author(s):  
Poirot Nathalie ◽  
Raynal Pierre-Ivan
Keyword(s):  
Spin Coating ◽  
Three Dimensional ◽  
Precursor Solution ◽  
Solution Viscosity ◽  
Chemical Solution ◽  
New Approach ◽  
Conformal Coating ◽  
Si Substrates ◽  
Aspect Ratios ◽  
Post Annealing

We demonstrated a new approach to the production of three-dimensional-coated patterns using liquid route. Metallic perovskite oxides were coated onto three-dimensional (3D) microstructured substrates with different aspect ratios. The success of the method relies on the solution viscosity monitored by adding viscous liquid. The process of oxide thin films consists in three steps: preparing the precursor solution, coating the solution by spin-coating process onto three-dimensional-Si substrates and post-annealing. The chemical solution 3D-coating is conformal.

scholarly journals Low-Zpolymer sample supports for fixed-target serial femtosecond X-ray crystallography

2015 ◽  
Vol 48 (4) ◽  
pp. 1072-1079 ◽  
Author(s):  
Geoffrey K. Feld ◽  
Michael Heymann ◽  
W. Henry Benner ◽  
Tommaso Pardini ◽  
Ching-Ju Tsai ◽  
...  
Keyword(s):  
Protective Antigen ◽  
Three Dimensional ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
Fixed Target ◽  
X Ray ◽  
X Ray Crystallography ◽  
Transmission Electron ◽  
Linac Coherent Light Source ◽  
Efficient Alternative

X-ray free-electron lasers (XFELs) offer a new avenue to the structural probing of complex materials, including biomolecules. Delivery of precious sample to the XFEL beam is a key consideration, as the sample of interest must be serially replaced after each destructive pulse. The fixed-target approach to sample delivery involves depositing samples on a thin-film support and subsequent serial introductionviaa translating stage. Some classes of biological materials, including two-dimensional protein crystals, must be introduced on fixed-target supports, as they require a flat surface to prevent sample wrinkling. A series of wafer and transmission electron microscopy (TEM)-style grid supports constructed of low-Zplastic have been custom-designed and produced. Aluminium TEM grid holders were engineered, capable of delivering up to 20 different conventional or plastic TEM grids using fixed-target stages available at the Linac Coherent Light Source (LCLS). As proof-of-principle, X-ray diffraction has been demonstrated from two-dimensional crystals of bacteriorhodopsin and three-dimensional crystals of anthrax toxin protective antigen mounted on these supports at the LCLS. The benefits and limitations of these low-Zfixed-target supports are discussed; it is the authors' belief that they represent a viable and efficient alternative to previously reported fixed-target supports for conducting diffraction studies with XFELs.

Epitaxial Growth of Aluminum Nitride on Sapphire and Silicon

1994 ◽  
Vol 358 ◽  
Author(s):  
K. Dovidenko ◽  
S. Oktyabrsky ◽  
J. Narayan ◽  
M. Razeghi
Keyword(s):  
Epitaxial Growth ◽  
Substrate Surface ◽  
Wide Band ◽  
X Ray Diffraction ◽  
Wide Band Gap ◽  
High Quality ◽  
Microstructural Characteristics ◽  
X Ray ◽  
Si Substrates ◽  
Transmission Electron

ABSTRACTThe microstructural characteristics of wide band gap semiconductor, hexagonal A1N thin films on Si(100), (111), and sapphire (0001) and (10ī2) were studied by transmission electron microscopy (TEM) and x-ray diffraction. The films were grown by MOCVD from TMA1 + NH3 + N2 gas mixtures. Different degrees of film crystallinity were observed for films grown on α-A12O3 and Si substrates in different orientations. The epitaxial growth of high quality single crystalline A1N film on (0001) α-Al2O3 was demonstrated with a dislocation density of about 2*10 10cm−2 . The films on Si(111) and Si(100) substrates were textured with the c-axis of A1N being perpendicular to the substrate surface.

Pulsed Ion-Beam Induced Reactions of Ni And Co With Amorphous and Single Crystal Silicon

1984 ◽  
Vol 35 ◽  
Author(s):  
J. O. Olowolafe ◽  
R. Fastow
Keyword(s):  
Amorphous Silicon ◽  
Ion Beam ◽  
Single Crystal Silicon ◽  
Reaction Rates ◽  
Rutherford Backscattering ◽  
Thin Layers ◽  
X Ray Diffraction ◽  
Furnace Annealing ◽  
Crystal Silicon ◽  
Transmission Electron

ABSTRACTThin layers (~1,000 A ) of Ni and Co have been reacted with both (100) and amorphous silicon (a-Si) using a pulsed ion beam. Samples were analyzed using Rutherford backscattering, x-ray diffraction, and transmission electron microscopy. Rutherford backscattering showed that the metal/a-Si and metal/(100)-Si reaction rates were comparable. Both reactions began at the composition of the lowest eutectic. For comparison. furnace annealing of the same structures showed that the reaction rate of Ni with amorphous silicon was greater than with (100) Si; Co reacted nearly identically with both substrates. Diffraction data suggest that pulsed ion beam annealing crystallizes the amorphous silicon before the metal/a-Si reaction begins.

Algorithms for the calculation of X-ray diffraction patterns from finite element data

2010 ◽  
Vol 43 (6) ◽  
pp. 1287-1299 ◽  
Author(s):  
E. Wintersberger ◽  
D. Kriegner ◽  
N. Hrauda ◽  
J. Stangl ◽  
G. Bauer
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Point Of View ◽  
X Ray Diffraction ◽  
Displacement Fields ◽  
X Ray ◽  
Si Substrates ◽  
Diffraction Patterns ◽  
Simulation Point ◽  
Ccd Detectors

A set of algorithms is presented for the calculation of X-ray diffraction patterns from strained nanostructures. Their development was triggered by novel developments in the recording of scattered intensity distributions as well as in simulation practice. The increasing use of two-dimensional CCD detectors in X-ray diffraction experiments, with which three-dimensional reciprocal-space maps can be recorded in a reasonably short time, requires efficient simulation programs to compute one-, two- and three-dimensional intensity distributions. From the simulation point of view, the finite element method (FEM) has become the standard tool for calculation of the strain and displacement fields in nanostructures. Therefore, X-ray diffraction simulation programs must be able to handle FEM data properly. The algorithms presented here make use of the deformation fields calculated on a mesh, which are directly imported into the calculation of diffraction patterns. To demonstrate the application of the developed algorithms, they were applied to several examples such as diffraction data from a dislocated quantum dot, from a periodic array of dislocations in a PbSe epilayer grown on a PbTe pseudosubstrate, and from ripple structures at the surface of SiGe layers deposited on miscut Si substrates.

MO-CVD GaAs Grown by Direct Deposition on Si

1987 ◽  
Vol 91 ◽  
Author(s):  
S. M. Vernon ◽  
S. J. Pearton ◽  
J. M. Gibson ◽  
R. Caruso ◽  
C. R. Abernathy ◽  
...  
Keyword(s):  
Chemical Vapor ◽  
Gaas Layer ◽  
Threading Dislocation ◽  
X Ray Diffraction ◽  
Si Substrates ◽  
Transmission Electron ◽  
Activation Data ◽  
Threading Dislocation Density ◽  
Donor Activity

ABSTRACTGaAs layers were grown directly on misoriented (2° off (100)→[011]) Si substrates by Metalorganic Chemical Vapor Deposition. The threading dislocation density at the surface of 4 μm thick layers was typically 108cm−2, as determined by both preferential etching and transmission electron microscopy. Rapid thermal annealing (900°C, 10s) improved the crystalline quality of the GaAs near the heterointerface while allowing no detectable Si diffusion into this layer. Two deep electron traps were observed in the undoped GaAs, but were present at a low concentration (∼ 1013 cm−3 ). The (400) x-ray diffraction peak width from the GaAs was significantly reduced with increasing GaAs layer thickness, indicating improved material quality. This is supported by Si implant activation data, which shows higher net donor activity in thicker layers.

Three-dimensional morphology of anatase nanocrystals obtained from supercritical flow synthesis with industrial grade TiOSO4 precursor

2019 ◽  
Vol 75 (6) ◽  
pp. 1086-1095 ◽  
Author(s):  
Jinlong Yu ◽  
Frederik Søndergaard-Pedersen ◽  
Aref Mamakhel ◽  
Paolo Lamagni ◽  
Bo Brummerstedt Iversen
Keyword(s):  
Three Dimensional ◽  
High Specific Surface Area ◽  
X Ray Diffraction ◽  
Titanyl Sulfate ◽  
Supercritical Flow ◽  
Price Expectation ◽  
X Ray ◽  
Industrial Grade ◽  
Transmission Electron ◽  
Dimensional Reconstruction

Anatase TiO2 (a-TiO2) nanocrystals are vital in catalytic applications both as catalysts (e.g. photodegradation) and as a carrier material (e.g. NOx removal from exhaust). The synthesis of a-TiO2 nanocrystals and their properties have been heavily scrutinized, but there exists a clear gap between the scientific literature, and the scale and price expectation of industrial application. Here it is demonstrated that the industrially most attractive Ti precursor, titanyl sulfate (TiOSO4), can be combined with the green, scalable and fast supercritical flow method to produce phase pure and highly crystalline a-TiO2 nanoparticles with high specific surface area. Control of the nanocrystal morphology is important since it is known that certain facets substantially promote catalytic activity. It is, however, in itself challenging to determine nanocrystal morphology to provide a rational basis for the synthesis control. Here we advocate the use of advanced Rietveld refinement of powder X-ray diffraction data including anisotropic size broadening models in aiding to establish the sample three-dimensional morphology. This relatively quick and robust method assists in overcoming the often encountered ambiguity inherent in two-dimensional to three-dimensional reconstruction of selected particle morphologies with transmission electron microscopy and tomography techniques.

scholarly journals Transmission Electron Microscopy and X-ray Diffraction Investigation of the Microstructure of Nanoscale Multilayer TiAlN/VN Grown by Unbalanced Magnetron Deposition

2004 ◽  
Vol 19 (4) ◽  
pp. 1093-1104 ◽  
Author(s):  
Q. Luo ◽  
D.B. Lewis ◽  
P.Eh. Hovsepian ◽  
W-D. Münz
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Growth Model ◽  
Growth Front ◽  
Columnar Structure ◽  
Layer Growth ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Unbalanced Magnetron

Cubic NaCl-B1 structured multilayer TiAlN/VN with a bi-layer thickness of approximately 3 nm and atomic ratios of (Ti+Al)/V = 0.98 to 1.15 and Ti/V = 0.55 to 0.61 were deposited by unbalanced magnetron sputtering at substrate bias voltages between -75 and -150 V. In this paper, detailed transmission electron microscopy and x-ray diffraction revealed pronounced microstructure changes depending on the bias. At the bias -75 V, TiAlN/VN followed a layer growth model led by a strong (110) texture to form a T-type structure in the Thornton structure model of thin films, which resulted in a rough growth front, dense columnar structure with inter-column voids, and low compressive stress of -3.8 GPa. At higher biases, the coatings showed a typical Type-II structure following the strain energy growth model, characterized by the columnar structure, void-free column boundaries, smooth surface, a predominant (111) texture, and high residual stresses between -8 and -11.5 GPa.

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