GaN On 6H-SiC – Structural And Optical Properties

1994 ◽  
Vol 339 ◽  
Author(s):  
C. Wetzel ◽  
D. Volm ◽  
B. K. Meyer ◽  
K. Pressel ◽  
S. Nilsson ◽  
...  
Keyword(s):  
Optical Properties ◽  
Transition Metal Ions ◽  
Substrate Material ◽  
X Ray Diffraction ◽  
High Quality ◽  
Paramagnetic Resonance ◽  
Lattice Constants ◽  
Donor Acceptor ◽  
Related Donor

ABSTRACTRecent progress in the growth of high quality 6H-SiC single crystals has led to an ideal substrate material for GaN epitaxial films. Nearly matching lattice constants of wurzite GaN to 6H-SiC in the hexagonal plane can reduce strain effects at the interface. We employed the sublimation sandwich method to grow single crystal layers at reasonable growth rates with free carrier concentrations of 2×1017 cm-3. Very sharp x-ray diffraction peaks of the GaN (0002) plane are obtained indicating the high quality of this system (Δ(2θ) < 0.1 degrees). These findings are directly reflected in the optical properties. The photoluminescence is dominated by a single sharp exciton line, impurity related donor acceptor transitions are seen with very weak intensities. However, at lower energies the internal luminescence transitions of the 3d transition metal ions Fe and V are observable. The incorporation of Fe is confirmed by electron paramagnetic resonance.

Cyclo-thiazenokomplexe von Vanadium(V) Die Kristallstruktur von (AsPh4)2[V(N3)3(N3S2)]2 · CH2Cl2 / Cyclo-thiazeno Complexes of Vanadium(V) The Crystal Structure of (AsPh4)2[V(N3)3(N3S2)]2 · CH2Cl2

1984 ◽  
Vol 39 (12) ◽  
pp. 1686-1695 ◽  
Author(s):  
Jürgen Hanich ◽  
Magda Krestel ◽  
Ulrich Müller ◽  
Kurt Dehnicke ◽  
Dieter Rehder
Keyword(s):  
Crystal Structure ◽  
Diffraction Data ◽  
Nmr Spectra ◽  
Formula Unit ◽  
X Ray Diffraction ◽  
Triclinic Space Group ◽  
X Ray ◽  
Lattice Constants ◽  
Nmr Data ◽  
Donor Acceptor

An improved synthesis for [VCl2(N3S2)]∞, was found in the reaction of VOCl3 with (NSCl)3; when the reaction is performed in H2CCl2 and (NSCl)3 is used in excess, the thiazyl-solvate [VCl2(N3S2) · NSCl]2 is obtained. [VCl2(N3S2)] reacts with AsPh4Cl to form (AsPh4)2[VCl3(N 3S2)]2; this reacts with AgN3 in CH2Cl2 suspension to yield (AsPh4)2[V (N3)3(N3S2)]2 · CH2Cl2. The compounds were characterized by their IR and 51V NMR spectra. The latter are compared with new 51V NMR data for [VO2Cl2]⊖ and [VOCl4]⊖ ; a decrease of 51V shielding in the order [VO2Cl2]⊖ > [VOCl4]⊖ > [VX3(N3S2)]22⊖ (X - N3 > Cl) is found, which is interpreted in terms of increasing polarizability of the ligands and of ring contributions to the extreme deshielding observed with the thiazenovanadates.The crystal structure of (AsPh4)2[V(N3)3(N3S2)]2 · CH2Cl2 was determined from X-ray diffraction data (1496 observed reflexions, R = 0.058). It crystallizes in the triclinic space group P 1̄ with one formula unit per unit cell and with the lattice constants a - 1087, b = 1317, c = 1350 pm, α = 58.8, β = 85.9, γ = 68.0°. The structure consists of AsPh4⊕ ions, CH2Cl2 molecules and centrosymmetric [V(N3)3(N3S2)]22⊖ anions. In the latter. N3S2 ligands are bonded to the V atoms in a chelate manner with short V = N bonds (189 and 172 pm) forming planar VN3S2 rings. The dimerization is accomplished by V -N donor-acceptor interactions (224 pm) involving one N atom of each VN3S2 ring. The vanadium coordination number of 6 is com pleted by three azido groups with V -N bond distances of 200 to 204 pm.

scholarly journals Comparison of the Quality of Protein Crystals Grown by CLPC Seeds Method

Crystals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 501 ◽  
Author(s):  
Li ◽  
Yan ◽  
Liu ◽  
Wu ◽  
Liu ◽  
...  
Keyword(s):  
Diffraction Data ◽  
Protein Crystal ◽  
Protein Crystals ◽  
X Ray Diffraction ◽  
High Quality ◽  
X Ray ◽  
High Quality Protein

We present a systematic quality comparison of protein crystals obtained with and without cross-linked protein crystal (CLPC) seeds. Four proteins were used to conduct the experiments, and the results showed that crystals obtained in the presence of CLPC seeds exhibited a better morphology. In addition, the X-ray diffraction data showed that the CLPC seeds method is a powerful tool to obtain high-quality protein crystals. Therefore, we recommend the use of CLPC seeds in preparing high-quality diffracting protein crystals.

Evaluation of Optical Properties for Nanocrystal Si Dot Layers Fabricated by CVD as a Function of Size Reduction

2012 ◽  
Vol 725 ◽  
pp. 251-254
Author(s):  
Yuki Mizukami ◽  
D. Kosemura ◽  
M. Takei ◽  
Y. Numasawa ◽  
Y. Ohshita ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Optical Properties ◽  
Quantum Confinement ◽  
Vapour Deposition ◽  
Chemical Vapour ◽  
X Ray Diffraction ◽  
Confinement Effects ◽  
Quantum Confinement Effects ◽  
Transmission Electron

Raman spectroscopy and photoluminescence were performed in order to understand the optical properties of nanocrystal Si in relation to quantum confinement effects. The nanocrystal Si (nc-Si) dots in the SiO2 layer were fabricated by the H2 plasma treatment and chemical vapour deposition followed by the oxidation of the nc-Si dots surface. The post-annealing was also performed to improve the crystalline quality of nc-Si at 1050 °C for 5 and 10 min. There is a good correlation of the quantum confinement effects between the results of Raman spectroscopy and photoluminescence. The Raman spectra from nc-Si were analysed using the model of Richter et al. As a result, the sizes of the nc-Si dots were consistent with those obtained by transmission electron microscopy and X-ray diffraction. Moreover, the compressive stress in the nc-Si dots were evaluated which was induced by the SiO2 surroundings.

Ferroelectric domain structure of epitaxial (Pb,Sr)TiO3 thin films

2001 ◽  
Vol 16 (9) ◽  
pp. 2463-2466 ◽  
Author(s):  
Yong Kwan Kim ◽  
Kyeong Seok Lee ◽  
Sunggi Baik
Keyword(s):  
Thin Films ◽  
Curie Temperature ◽  
Transformation Strain ◽  
Systematic Change ◽  
X Ray Diffraction ◽  
Axis Orientation ◽  
Rocking Curve ◽  
Lattice Constants ◽  
Ferroelectric Domain Structure

Epitaxial (Pb1−xSrx)TiO3 (PST, x = 4 0.0–0.24) thin films were grown on MgO(001) single-crystal substrates by pulsed laser deposition. General x-ray diffraction techniques including θ–2θ scan and rocking curve were used to determine lattice constants, degree of c-axis orientation, and crystal quality of the tetragonal thin films. The degree of c-axis orientation in the epitaxial PST films increased as Sr concentration (x) increased, which in turn induces the systematic change in the Curie temperature as well as the transformation strain at and below the Curie temperature. An inverse relation between the c-domain abundances and the transformation strains is established.

New Ge-Sn materials with adjustable bandgaps and lattice constants

2002 ◽  
Vol 744 ◽  
Author(s):  
Matthew R. Bauer ◽  
John Tolle ◽  
A. V. G. Chizmeshya ◽  
S. Zollner ◽  
J. Menendez ◽  
...  
Keyword(s):  
Optical Properties ◽  
Secondary Ion Mass Spectrometry ◽  
Compositional Dependence ◽  
X Ray Diffraction ◽  
Chemical Methods ◽  
Lattice Constants ◽  
New Class ◽  
Transmission Electron ◽  
Wide Range ◽  
Secondary Ion

ABSTRACTThe synthesis and optical properties of a new class of Si-based infrared semiconductors in the Ge1-x Snx system are described. Chemical methods based on deuterium-stabilized Sn hydrides and UHV-CVD were used to prepare a wide range of metastable compositions and structures directly on silicon. These materials exhibit high thermal stability, superior crystallinity, and unique crystallographic and optical properties, such as adjustable band gaps and lattice constants. These properties are characterized by Rutherford backscattering, low-energy secondary ion mass spectrometry, high-resolution transmission electron microscopy, x-ray diffraction as well as infrared and Raman spectroscopies and spectroscopic ellipsometry. The films grow essentially strain free and display a strong compositional dependence of the band structure.

Die Kristallstrukturen der Cyclothiazenokomplexe [MoCl3(N3S2)(Pyridin)] und [MoCl3(N3S2)(Tetrahydrofuran)] / The Crystal Structures of the Cyclothiazeno-Complexes [MoCl3(N3S2)(Pyridine)] and [MoCl3(N3S2)(Tetrahydrofurane)]

1986 ◽  
Vol 41 (10) ◽  
pp. 1196-1200 ◽  
Author(s):  
Karin Völp ◽  
Wolfgang Willing ◽  
Ulrich Müller ◽  
Kurt Dehnicke
Keyword(s):  
Crystal Structures ◽  
Dihedral Angles ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lattice Constants ◽  
Donor Acceptor ◽  
Molybdenum Pentachloride ◽  
In Trans ◽  
Moisture Sensitive

An improved method of synthesis for MoCl3(N3S2) from molybdenum pentachloride and trithiazylchloride is given. Its reaction with pyridine and tetrahydrofuran in a CH2Cl2 suspension yields the donor-acceptor complexes [MoCl3(N3S2)(C5H5N)] and [MoCl3(N3S2)(C4H8O)], respectively. Both are soluble in CH2Cl2 and can be obtained in form of black, moisture sensitive crystals. Their IR spectra are reported and their crystal structures were determined by X-ray diffraction. Both compounds have nearly the same structure (monoclinic, space group P21/c, Z = 4). Lattice constants: [MoCl3(N3S2)(C5H5N)], a = 1102.2, b = 997.7, c = 1134.9 pm, α = 94.19° (1582 observed, independent reflexions, R = 0.023); [MoCl3(N3S2)(C4H8O)], a = 1069.7, b = 1002.5, c = 1122.0 pm, β = 93.77° (1440 reflexions, R = 0.024). In the molecules, the Mo atoms are members of nearly planar MoN3S2 rings with MoN bond distances between 178 and 185 pm , which correspond to double bonds. The sixfold coordination of the Mo atoms is completed by three chlorine atoms and the N or O atom of the pyridine or tetrahydrofuran ligand, respectively. The solvate molecules are in trans positions to one of the N atoms and form dihedral angles of 34.0° and 41.4° with the M oN3S2 rings, respectively.

scholarly journals Floating Zone Growth of Sr Substituted Han Purple: Ba0.9Sr0.1CuSi2O6

Crystals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 273
Author(s):  
Pascal Puphal ◽  
Stephan Allenspach ◽  
Christian Rüegg ◽  
Ekaterina Pomjakushina
Keyword(s):  
Magnetic Susceptibility ◽  
Single Crystals ◽  
Inelastic Neutron ◽  
Floating Zone ◽  
X Ray Diffraction ◽  
High Quality ◽  
Single Crystal Diffraction ◽  
X Ray ◽  
Zone Growth

We present a route to grow single crystals of Ba 0.9 Sr 0.1 CuSi 2 O 6 suitable for inelastic neutron studies via the floating zone technique. Neutron single crystal diffraction was utilized to check their bulk quality and orientation. Finally, the high quality of the grown crystals was proven by X-ray diffraction and magnetic susceptibility.

Mineralogy and technological characterization of two kaolin deposits from the Borborema Pegmatite Province, northeastern Brazil

Clay Minerals ◽  
2019 ◽  
Vol 54 (3) ◽  
pp. 283-291
Author(s):  
Victor Matheus Joaquim Salgado Campos ◽  
Luiz Carlos Bertolino ◽  
Luana Caroline Silveira Nascimento ◽  
José Yvan Pereira Leite ◽  
Vitor Schwenk Brandão ◽  
...  
Keyword(s):  
Optical Properties ◽  
Magnetic Separation ◽  
Chemical Characterization ◽  
Northeastern Brazil ◽  
X Ray Diffraction ◽  
Paramagnetic Resonance ◽  
X Ray ◽  
Structural Formulae

AbstractThis research presents the mineralogical and chemical characterization and beneficiation study of two kaolin deposits from the Borborema Pegmatite Province, Brazil. Seven samples were collected and treated in two different beneficiation routes involving magnetic separation and chemical bleaching. The fractions obtained were studied by X-ray diffraction, X-ray fluorescence spectrometry, scanning electron microscopy, particle-size analyses, electron paramagnetic resonance and determination of optical properties. The samples are composed mainly of subhedral kaolinite in the form of booklets, as well as muscovite, quartz, microcline and illite impurities. The kaolinite structural formulae indicated significant replacement of Si4+ by Al3+ in tetrahedral sites and low replacement of Fe3+ by Al3+ in the octahedral sites. The first 30 min of chemical bleaching improved significantly the optical properties of kaolin, indicating that the process is more efficient than magnetic separation.

High Quality GaP Growth on Si Substrates By Mocvd

1988 ◽  
Vol 116 ◽  
Author(s):  
K. Uchida ◽  
Y. Kohama ◽  
M. Tajima ◽  
T. Soga ◽  
T. Jimbo ◽  
...  
Keyword(s):  
Mass Spectroscopy ◽  
Diffraction Peak ◽  
Crystal Quality ◽  
X Ray Diffraction ◽  
High Quality ◽  
Double Crystal ◽  
X Ray ◽  
Si Substrates ◽  
Secondary Ion

AbstractGaP crystals are grown on Si substrates by MOCVD. Double crystal X-ray diffraction indicates that the crystal quality of GaP layers greatly improves when AsH3 is supplied before growth. The FWHM of (400) diffraction peak of the GaP layer decreases as the thickness increases and the best FWHM of 112.5 arcs is obtained at a thickness of 5 μm. The GaP/Si interface is characterized using secondary ion mass spectroscopy (SIMS) to demonstrate the effect of AsH3.

Growth of CuInGaSe2 Films by RF Sputtering Using CuInGaSe2 Single Phase Target

2013 ◽  
Vol 372 ◽  
pp. 571-574
Author(s):  
Kenji Yoshino ◽  
Takahiro Tokuda ◽  
Akira Nagaoka ◽  
Kenichiro Miseki ◽  
Rie Mori ◽  
...  
Keyword(s):  
Room Temperature ◽  
Single Phase ◽  
Rf Sputtering ◽  
Diffraction Peak ◽  
Secondary Phases ◽  
X Ray Diffraction ◽  
High Quality ◽  
Homogeneous Surface ◽  
X Ray

CuIn0.8Ga0.2Se2 thin film is grown at room temperature by RF sputtering using high quality of CuIn0.8Ga0.2Se2 single phase target. A (112) diffraction peak is dominant with no secondary phases such as selenide materials in the X-ray diffraction pattern. A flat and homogeneous surface can be obtained in the sample.

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