scholarly journals Crystalline Growth of Wurtzite GaN on (111) GaAs

1992 ◽  
Vol 242 ◽  
Author(s):  
J. Ross ◽  
M. Rubin ◽  
T. K. Gustafson
Keyword(s):  
Full Width Half Maximum ◽  
Lattice Mismatch ◽  
Rf Magnetron Sputtering ◽  
X Ray Diffraction ◽  
X Ray ◽  
Gaas Substrates ◽  
Surface Reconstructions ◽  
Diffraction Patterns ◽  
Reactive Rf Magnetron Sputtering ◽  
Crystalline Growth

ABSTRACTGallium Nitride films were grown on (111) Gallium Arsenide substrates using reactive rf magnetron sputtering. Despite a 20% lattice mismatch and different crystal structure, wurtzite GaN films grew epitaxially in basal orientation on (111) GaAs substrates. Heteroepitaxy was observed for growth temperatures between 550–600°C. X-ray diffraction patterns revealed (0002) GaN peak with a full-width-half-maximum (FWHM) as narrow as 0.17°. Possible surface reconstructions to explain the epitaxial growth are presented.

Direct preparation and microstructure investigation of p-type transparent conducting Ga-doped SnO2 thin films

2010 ◽  
Vol 25 (S1) ◽  
pp. S36-S39 ◽  
Author(s):  
Tieying Yang ◽  
Xiubo Qin ◽  
Huan-hua Wang ◽  
Quanjie Jia ◽  
Runsheng Yu ◽  
...  
Keyword(s):  
Thin Films ◽  
Rf Magnetron Sputtering ◽  
Photoelectron Spectra ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fine Microstructure ◽  
Direct Preparation ◽  
Sno2 Thin Films ◽  
P Type ◽  
Reactive Rf Magnetron Sputtering

Transparent p-type conducting Ga-doped SnO2 thin films were prepared using reactive rf-magnetron sputtering. Good p-type conduction was directly realized without the need of postdeposition annealing. The p-type conductivity was found to be very sensitive to the growth condition and process, suggesting that the carrier behavior is strongly related to the fine microstructure of the films. The microstructures of the films were characterized using synchrotron X-ray diffraction and specular reflectivity techniques. The valence state of the Ga dopant was measured from X-ray photoelectron spectra to explain the origin of net holes presented in the films.

Growth and Magnetic Properties of La0.65Pb0.35MnO3 Films

1999 ◽  
Vol 602 ◽  
Author(s):  
Q. L. Xu ◽  
M. T. Liu ◽  
Y. Liu ◽  
C. N. Borca ◽  
H. Dulli ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Defect Density ◽  
Rf Magnetron Sputtering ◽  
Scanning Tunneling ◽  
X Ray Diffraction ◽  
Tunneling Microscopy ◽  
X Ray ◽  
Bulk Magnetization ◽  
Low Energy Electron ◽  
Diffraction Patterns

AbstractWe have successfully grown La0.65PbO.35MnO3 thin films by a RF magnetron sputtering method onto (100) LaAlO3 single crystal substrates. X-ray diffraction measurements are consistent with a (100) cubic orientation of the films. The fourfold symmetry showed by LEED(Low Energy Electron Diffraction) patterns indicate that the films have surface order. STM(Scanning Tunneling Microscopy) measurements indicate that the surface of the films were smooth, with approximate 5 nm roughness. XPS (X-ray Photoemission Spectroscopy) shows that the surface defect density in the films is comparatively low. The bulk magnetization of the films at 6K in 1 T magnetic field reached 77 emu/g and a Curie temperature near 354 K, close to maximum resistivity. A negative magnetoresistance of 47% was observed at 320K in 5.5 T magnetic field.

Quaternary Alloys InxAlyGa1−x-yAs Grown on GaAs with A Compositionally-Step-Graded Buffer

1992 ◽  
Vol 263 ◽  
Author(s):  
C. Fan ◽  
D. W. Shih ◽  
M. W. Hansen ◽  
J. Chen ◽  
P. Z. Lee ◽  
...  
Keyword(s):  
Schottky Barrier ◽  
Lattice Mismatch ◽  
Chemical Reactivity ◽  
Compressive Strain ◽  
X Ray Diffraction ◽  
Quaternary Alloys ◽  
X Ray ◽  
Mismatch Strain ◽  
Barrier Heights ◽  
Gaas Substrates

ABSTRACTFundamental bandgaps and Schottky barrier heights of strain-relaxed quaternary InxAlyGa1−x-yAs alloys with 0 < x < 0.35 and 0 < y < 0.30 were studied. The alloys were grown on GaAs substrates by molecular beam epitaxy. The lattice mismatch (up to 2.5%) and mismatch strain were accommodated by a compositionally-step-graded buffer. A residual compressive strain of less than 0.5% was determined by x-ray diffraction. Measured Schottky barrier heights v.s. bandgap deviate from the values predicted by the “commonanion” rule. This behavior is attributed to the compositional inhomogeneities and chemical reactivity of the air-exposed InAlGaAs surfaces.

X-ray diffraction study of a one-dimensional GaAs–AlAs superlattice

1977 ◽  
Vol 10 (1) ◽  
pp. 1-6 ◽  
Author(s):  
A. Segmüller ◽  
P. Krishna ◽  
L. Esaki
Keyword(s):  
Elastic Strain ◽  
Lattice Mismatch ◽  
Reciprocal Lattice ◽  
Unit Cell ◽  
Scattering Data ◽  
High Angle ◽  
X Ray Diffraction ◽  
One Dimensional ◽  
X Ray ◽  
Diffraction Patterns

Low- and high-angle X-ray diffraction patterns have been obtained from one-dimensional superlattice crystals prepared artificially by alternately depositing predetermined thicknesses of GaAs and AlAs, on the (001) face of a GaAs single-crystal by molecular-beam epitaxy. The positions and intensities of several superlattice reflections obtained along the 00l, 11l and 02l reciprocal lattice rows have been recorded. The structure of the superlattice can be approximated by a model which incorporates elastic strains in the unit cell due to the lattice mismatch between GaAs and AlAs. The number of Ga and Al layers in the superlattice unit cell can be accurately determined from the low-angle scattering data while the relative intensities of the high-angle superlattice reflections are a sensitive measure of the elastic strain present in the lattice. It is shown that the elastic strain agrees with the value computed theoretically on the assumption that the strain is not relieved by dislocations at the GaAs–AlAs interfaces.

scholarly journals Cu 4O3 thin films deposited by non-reactive rf-magnetron sputtering from a copper oxide target

2021 ◽  
Vol 67 (3 May-Jun) ◽  
pp. 495
Author(s):  
M. A. Cruz Almazán ◽  
E. Vigueras Santiago ◽  
R. López ◽  
S. Hernández López ◽  
V. Hugo Castrejón Sánchez ◽  
...  
Keyword(s):  
Thin Films ◽  
Magnetron Sputtering ◽  
Copper Oxide ◽  
Cuprous Oxide ◽  
Cupric Oxide ◽  
Rf Magnetron Sputtering ◽  
X Ray Diffraction ◽  
Oxide Thin Films ◽  
X Ray ◽  
Reactive Rf Magnetron Sputtering

Copper oxide thin films deposited by sputtering are frequently formed by using metal copper targets in reactive atmospheres. In this report, paramelaconite (Cu4O3) thin films were deposited by non-reactive rf magnetron sputtering. The target used for sputtering was a copper oxide disk fabricated by oxidation of metal copper at 1000 °C for 24 h in airatmosphere. X-ray diffraction (XRD) results showed that the copper oxide target was mainly composed of cupric oxide (CuO) and cuprous oxide (Cu2O) crystals. Raman analyses suggested that the surface of the copper oxide disk is composed by a (CuO) layer. XRD measurements performed to the copper oxide thin films deposited by non-reactive rf magnetron sputtering showed that the film is composed of (Cu4O3) crystals. However,Raman measurements indicated that the Cu4O3 thin films are also composed by amorphous CuO and Cu2O.

Progress Toward Thin-Film LiNbO3 Waveguides on GaAs

1993 ◽  
Vol 329 ◽  
Author(s):  
J. J. Kingston ◽  
F. Leplingard ◽  
D. K. Fork
Keyword(s):  
Rf Magnetron Sputtering ◽  
X Ray Diffraction ◽  
Ferroelectric Films ◽  
X Ray ◽  
Force Microscopy ◽  
Electron Microscopies ◽  
Atomic Force ◽  
Gaas Substrates ◽  
Semiconductor Substrates ◽  
Waveguide Fabrication

AbstractThe availability of epitaxial ferroelectric films on semiconductor substrates would open up many options for integrated optics technology. There are significant materials issues involved in achieving this integration and we will report on progress toward optical waveguide fabrication on GaAs substrates. As a first step, we are investigating the fabrication of z-LiNbO3 waveguides on A12O3-c. The films have been deposited by off-axis rf magnetron sputtering and characterized by x-ray diffraction, atomic force microscopy, and scanning electron microscopies. Prism coupling has been used to determine waveguide thickness, indices of refraction and propogation losses. Issues concerning crystallography, texture, composition, surface roughness and processing will be discussed.

Structural and Electrical Properties of ZnO Films Deposited on GaAs Substrates by RF Magnetron Sputtering

1991 ◽  
Vol 238 ◽  
Author(s):  
Hong Koo Kim ◽  
Michelle Mathur
Keyword(s):  
Rf Magnetron Sputtering ◽  
Breakdown Field ◽  
Zno Films ◽  
Rf Power ◽  
X Ray Diffraction ◽  
X Ray ◽  
Gaas Substrates ◽  
Deposition Parameters ◽  
Structural And Electrical Properties ◽  
Deposited Films

ABSTRACTSputter deposition of ZnO films on GaAs substrates has been investigated. ZnO Alms were deposited using a ZnO compound target in Ar or Ar/O2 (95/5) ambient. Deposition parameters such as RF power, substrate-target distance, and gas composition/pressure were optimized to obtain highly c-axis oriented and highly resistive films. Deposited films were characterized by X-ray diffraction, scanning electron microscopy, capacitance, resistivity, and breakdown field strength measurements. X-ray diffraction measurements show a strong (0002)-plane peak with a full-width-half-maximum of less than 1°, indicating that the ZnO films deposited on GaAs substrates are highly c-axis oriented. DC resistivities of the films were measured to be on the order of 1011 Ω-cm.

Evaluation of Freezing Methods by Low Temperature X-Ray Diffraction

1977 ◽  
Vol 35 ◽  
pp. 330-333
Author(s):  
T. Gulik-Krzywicki ◽  
M.J. Costello
Keyword(s):  
Biological Materials ◽  
Molecular Organization ◽  
X Ray Diffraction ◽  
Glass Capillary ◽  
X Ray ◽  
Rate Dependent ◽  
Before And After ◽  
Freeze Etching ◽  
Diffraction Patterns ◽  
Set Up

Freeze-etching electron microscopy is currently one of the best methods for studying molecular organization of biological materials. Its application, however, is still limited by our imprecise knowledge about the perturbations of the original organization which may occur during quenching and fracturing of the samples and during the replication of fractured surfaces. Although it is well known that the preservation of the molecular organization of biological materials is critically dependent on the rate of freezing of the samples, little information is presently available concerning the nature and the extent of freezing-rate dependent perturbations of the original organizations. In order to obtain this information, we have developed a method based on the comparison of x-ray diffraction patterns of samples before and after freezing, prior to fracturing and replication.Our experimental set-up is shown in Fig. 1. The sample to be quenched is placed on its holder which is then mounted on a small metal holder (O) fixed on a glass capillary (p), whose position is controlled by a micromanipulator.

Examination of Rabbit Fc Crystals

1968 ◽  
Vol 26 ◽  
pp. 140-141
Author(s):  
J. P. Robinson ◽  
P. G. Lenhert
Keyword(s):  
Molecular Weight ◽  
Flat Plate ◽  
Phosphate Buffer ◽  
Asymmetric Unit ◽  
X Ray Diffraction ◽  
X Ray ◽  
Neutral Ph ◽  
Small Crystals ◽  
Carbon Coated ◽  
Diffraction Patterns

Crystallographic studies of rabbit Fc using X-ray diffraction patterns were recently reported. The unit cell constants were reported to be a = 69. 2 A°, b = 73. 1 A°, c = 60. 6 A°, B = 104° 30', space group P21, monoclinic, volume of asymmetric unit V = 148, 000 A°3. The molecular weight of the fragment was determined to be 55, 000 ± 2000 which is in agreement with earlier determinations by other methods.Fc crystals were formed in water or dilute phosphate buffer at neutral pH. The resulting crystal was a flat plate as previously described. Preparations of small crystals were negatively stained by mixing the suspension with equal volumes of 2% silicotungstate at neutral pH. A drop of the mixture was placed on a carbon coated grid and allowed to stand for a few minutes. The excess liquid was removed and the grid was immediately put in the microscope.

Control of the phase composition of advanced calcium phosphates using an x-ray diffractometer with a curved position-sensitive detector

2020 ◽  
Vol 86 (6) ◽  
pp. 29-35
Author(s):  
V. P. Sirotinkin ◽  
O. V. Baranov ◽  
A. Yu. Fedotov ◽  
S. M. Barinov
Keyword(s):  
Phase Composition ◽  
Calcium Phosphates ◽  
Position Sensitive Detector ◽  
Sensitive Detector ◽  
X Ray Diffraction ◽  
X Ray ◽  
Impurity Phases ◽  
Position Sensitive ◽  
Diffraction Peaks ◽  
Diffraction Patterns

The results of studying the phase composition of advanced calcium phosphates Ca10(PO4)6(OH)2, β-Ca3(PO4)2, α-Ca3(PO4)2, CaHPO4 · 2H2O, Ca8(HPO4)2(PO4)4 · 5H2O using an x-ray diffractometer with a curved position-sensitive detector are presented. Optimal experimental conditions (angular positions of the x-ray tube and detector, size of the slits, exposure time) were determined with allowance for possible formation of the impurity phases during synthesis. The construction features of diffractometers with a position-sensitive detector affecting the profile characteristics of x-ray diffraction peaks are considered. The composition for calibration of the diffractometer (a mixture of sodium acetate and yttrium oxide) was determined. Theoretical x-ray diffraction patterns for corresponding calcium phosphates are constructed on the basis of the literature data. These x-ray diffraction patterns were used to determine the phase composition of the advanced calcium phosphates. The features of advanced calcium phosphates, which should be taken into account during the phase analysis, are indicated. The powder of high-temperature form of tricalcium phosphate strongly adsorbs water from the environment. A strong texture is observed on the x-ray diffraction spectra of dicalcium phosphate dihydrate. A rather specific x-ray diffraction pattern of octacalcium phosphate pentahydrate revealed the only one strong peak at small angles. In all cases, significant deviations are observed for the recorded angular positions and relative intensity of the diffraction peaks. The results of the study of experimentally obtained mixtures of calcium phosphate are presented. It is shown that the graphic comparison of experimental x-ray diffraction spectra and pre-recorded spectra of the reference calcium phosphates and possible impurity phases is the most effective method. In this case, there is no need for calibration. When using this method, the total time for analysis of one sample is no more than 10 min.

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