Growth and Characterization of bulk GaN by Ga Vapor Transport

2004 ◽  
Vol 831 ◽  
Author(s):  
Phanikumar Konkapaka ◽  
Huaqiang Wu ◽  
Yuri Makarov ◽  
Michael G. Spencer
Keyword(s):  
Growth Rates ◽  
Vapor Transport ◽  
Spiral Growth ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Bulk Gan ◽  
Diffraction Patterns

ABSTRACTBulk GaN crystals of dimensions 8.5 mm × 8.5 mm were grown at growth rates greater than 200μm/hr using Gallium Vapor Transport technique. GaN powder and Ammonia were used as the precursors for growing bulk GaN. Nitrogen is used as the carrier gas to transport the Ga vapor that was obtained from the decomposition of GaN powder. During the process, the source GaN powder was kept at 1155°C and the seed at 1180°C. Using this process, it was possible to achieve growth rates of above 200 microns/hr. The GaN layers thus obtained were characterized using X-Ray diffraction [XRD], scanning electron microscopy [SEM], and atomic force microscopy [AFM]. X-ray diffraction patterns showed that the grown GaN layers are single crystals oriented along c direction. AFM studies indicated that the dominant growth mode was dislocation mediated spiral growth. Electrical and Optical characterization were also performed on these samples. Hall mobility measurements indicated a mobility of 550 cm2/V.s and a carrier concentration of 6.67 × 1018/cm3

Characterization of kaolinite in the hardsetting clay fraction using atomic force microscopy, X-ray diffraction, and the Rietveld method

2017 ◽  
Vol 17 (8) ◽  
pp. 2144-2155 ◽  
Author(s):  
Luis Valério Prandel ◽  
Nívea Maria Piccolomini Dias ◽  
Sérgio da Costa Saab ◽  
André Maurício Brinatti ◽  
Neyde Fabíola Balarezo Giarola ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Rietveld Method ◽  
Clay Fraction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force

Differential height characteristics of plasmid and G-wire DNA as determined by AFM

1994 ◽  
Vol 52 ◽  
pp. 1052-1053
Author(s):  
T. C. Marsh ◽  
J. Vesenka ◽  
E. Henderson
Keyword(s):  
Plasmid Dna ◽  
Structural Characteristics ◽  
Three Dimensional ◽  
Helical Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Dimension One

Atomic-Force Microscopy (AFM) has become an effective tool in the three dimensional characterization of biological systems and is capable of Angstrom sensitivity in the vertical dimension. One unresolved dilemma is that the observed height (diameter) of B-DNA being about 10Å, is less than half its x-ray diffraction value. In this paper we attempt to determine the source of this discrepancy by comparing plasmid DNA co-deposited with a novel form of DNA called “G-wires” (Figure 1). G-wires are formed by G-rich sequences. They are composed of G-4 DNA, a quadruple helical structure. X-ray data of G-4 DNA gives a diameter of 27Å, comparable to that expected for B-DNA (20 to 25Å). In the AFM these structures have a significantly greater height (av. = 22 Å) compared to double stranded (av. = 7 Å) or supercoiled B-DNA (av. = 14 Å) (Figure 2). Thus, the apparent height of nucleic acids in the AFM is dependent upon their innate structural characteristics.

Growth and Characterization of AlN and GaN Thin Films Deposited on Si(111) Substrates Containing a Very Thin Al Layer

2003 ◽  
Vol 798 ◽  
Author(s):  
Zachary J. Reitmeier ◽  
Robert F. Davis
Keyword(s):  
Flow Time ◽  
Buffer Layers ◽  
Nucleation Density ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Aln Buffer ◽  
Peak Widths

ABSTRACTAlN films and GaN films with AlN buffer layers were deposited via metalorganic vapor phase epitaxy on Si(111) substrates previously exposed to trimethylaluminum for increasing times. Atomic force microscopy (AFM) was used to determine the influence of Al pre-flow time on the nucleation and surface morphology of the AlN and GaN films. When preceded by a 10 second Al pre-flow, AlN films feature an increased and more uniform nucleation density as compared to films deposited without Al pre-flows. Ten second Al pre-flows were also found to result in a reduction of the RMS roughness for 100 nm thick AlN films from 3.6 nm to 1.0 nm. AFM of 0.5 μm thick GaN films deposited on AlN buffers with varying pre-flow times showed reduced roughness and decreased pit density when using Al pre-flows of 10 or 20 seconds. High resolution x-ray diffraction of the GaN films showed a reduction in the average full-width halfmaximum (FWHM) of the GaN (00.2) reflection from 1076 arcsec to 914 arcsec when the AlN buffer layer was initiated with a 10 second Al pre-flow. Increasing the pre-flow time to 20 seconds and 30 seconds resulted in average (00.2) FWHM values of 925 arcsec and 928 arcsec, respectively. Similar behavior of the peak widths was observed for the (30.2) and (10.3) reflections when the pre-flow times were varied from 0 to 30 seconds.

Characterization of a SiC/SiC composite by X-ray diffraction, atomic force microscopy and positron spectroscopies

2006 ◽  
Vol 252 (9) ◽  
pp. 3342-3351 ◽  
Author(s):  
G. Brauer ◽  
W. Anwand ◽  
F. Eichhorn ◽  
W. Skorupa ◽  
C. Hofer ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force

scholarly journals PREPARATION AND CHARACTERIZATION OF CDO-NIO NANOCOMPOSITES USING LASER PULSE DEPOSITION APPROACH

2021 ◽  
Vol 03 (03) ◽  
pp. 01-09
Author(s):  
Khamees D. MAHMOOD ◽  
Kadhim A. AADIM ◽  
Mohammed G. HAMMED
Keyword(s):  
Laser Pulse ◽  
Morphological Properties ◽  
X Ray Diffraction ◽  
Energy Band Gap ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Pulse Deposition ◽  
Deposited Films

In this manuscript, CdO-NiO nanocomposites (in the form of thin film) with particular concentrations are paper using laser pulse deposition technique under the effect of different laser energies (300, 400, 500, and 600 mJ). Furthermore, the structural, morphological, and optical analyses are thoroughly investigated. In particular, well-oriented deposited films are observed by using X-ray diffraction technique, while the morphological properties are investigated using two different techniques namely field emission scanning electron microscopy and atomic force microscopy which have revealed small nanoparticles with approximate diameter of 50 nm and average surface roughness ranging between 6.5 and 20.3 nm for laser energies of 400 and 600 mJ, respectively. Continuously, the optical technique applied which used UV-Vis analysis has showed cut-off phenomenon at around 339 nm. In the meanwhile, the energy band gap for the deposited films was found to be within the range of 2.2 and 2.4 eV, as a result of different laser energies.

AFM, HR-XRD AND PL CHARACTERIZATION OF STACKED STRUCTURES In0.5Ga0.5As/GaAs QUANTUM DOTS

NANO ◽  
2010 ◽  
Vol 05 (02) ◽  
pp. 127-132 ◽  
Author(s):  
DIDIK ARYANTO ◽  
ZULKAFLI OTHAMAN ◽  
AMIRA S. AMERUDDIN ◽  
ABD. KHAMIM ISMAIL
Keyword(s):  
Quantum Dots ◽  
Room Temperature ◽  
Size Composition ◽  
X Ray Diffraction ◽  
Satellite Peak ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Vertically Aligned

In0.5Ga0.5As quantum dots (QDs) stacked structure were studied using atomic force microscopy (AFM), high-resolution X-ray diffraction (HR-XRD) and photoluminescence (PL) characterization. Evolution in the dots size and dots density in the stacked structures is strongly influenced by the dot formation in the under-layer and the structure of the spacer layers. AFM results revealed that the dots formation on the top can be changed by increasing the number of stacked QDs. However, the dots formation is not vertically aligned since HR-XRD measurement gave different satellite peak on n-stacked QD structures. Room-temperature PL measurements show variation in the PL spectra, where blue-shifted PL peak positions are observed when the number of stack is increased. Variation in the HR-XRD and PL measurement is also attributed to the size, composition and density of the dots in the stacked structures.

Synthesis and Characterization of ZnO Nanorods Using Molecular Beam Epitaxy

2012 ◽  
Vol 622-623 ◽  
pp. 919-924 ◽  
Author(s):  
M. Asghar ◽  
Khalid Mahmood ◽  
M. Yasin Raja ◽  
M.A. Hasan
Keyword(s):  
Raman Spectroscopy ◽  
Zno Nanorods ◽  
X Ray Diffraction ◽  
Type Conductivity ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Capacitance Voltage ◽  
Vertically Aligned

We present the study of the growth of ZnO nanorods on p-Si (100) using MBE. Various characterization techniques such as Fourier transform infra-red (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), Raman spectroscopy and capacitance – voltage (C-V) measurements were employed to analyze and assess the grown ZnO nanorods. AFM clearly demonstrated the growth of vertically aligned nanorods, however, they get diffused as the thickness of the layer is increased beyond 1 µm. C-V measurements in particular, justified p-n junction between Si/ZnO nanorods. The junction showed n-type conductivity with carrier concentration 1×1015cm-3. The source of this n-type conductivity was Zn-interstitials and the presence of Zn-interstitials was confirmed by EDAX and Raman spectroscopy. Experimental detail and results were presented that help in furtherance of our understanding of the material issues and its potential as required for the practical devices.

scholarly journals Sol-gel synthesis and study of neodymium substitution effects in Co-Al-Nd-O system with possible applications as novel inorganic pigments

2012 ◽  
Vol 10 (5) ◽  
pp. 1574-1583 ◽  
Author(s):  
Dalia Jonynaite ◽  
Darius Jasaitis ◽  
Rimantas Raudonis ◽  
Algirdas Selskis ◽  
Remigijus Juskenas ◽  
...  
Keyword(s):  
Sol Gel ◽  
Substitution Effects ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Sol Gel Process ◽  
New Compounds ◽  
Sol Gel Synthesis

AbstractIn the present work, the formation of cobalt aluminium spinel (CoAl2O4) as well as novel cobalt neodymium-aluminates with nominal compositions of CoAl1.75Nd0.25O4, CoAl1.5Nd0.5O4 and CoAlNdO4 by an aqueous sol-gel process and the sinterability of the products are investigated. The metal ions, generated by dissolving starting materials of metals in the diluted acetic acid were complexed by 1,2-ethanediol to obtain the precursors for the mixed metal ceramics. The phase purity of the synthesized compounds was characterized by powder X-ray diffraction analysis and infrared spectroscopy. The microstructural evolution and morphological features of the products were studied by scanning electron microscopy and atomic force microscopy, which together with the optical characterization of these new compounds showed that the sol-gel-derived materials could be successfully used as effective cobalt-based ceramic pigments.

Characterization of Ultra-Thin PtSi Films for Infrared Detectors

1995 ◽  
Vol 402 ◽  
Author(s):  
H. Bender ◽  
P. Roussel ◽  
S. Kolodinski ◽  
A. Torres ◽  
R. A. Donaton ◽  
...  
Keyword(s):  
Grazing Incidence ◽  
X Ray Diffraction ◽  
Rapid Thermal Annealing Process ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Thermal Annealing Process ◽  
Deposition Techniques

AbstractTransmission electron microscopy and grazing incidence X-ray diffraction are used for the structural characterization of ultra-thin PtSi layers on (100) silicon prepared by a two-step rapid thermal annealing process. The roughness of the layers is investigated with atomic force microscopy. Two deposition techniques for the initial Pt layer are compared.

Continuous Carbon Nanofibers For Nanofiber Composites

2001 ◽  
Vol 702 ◽  
Author(s):  
Yuris Dzenis ◽  
Yongkui Wen
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanofibers ◽  
X Ray Diffraction ◽  
Electrospinning Technique ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Good Potential ◽  
Diffraction Patterns

ABSTRACTContinuous carbon nanofibers were manufactured using electrospinning technique. The as-spun polyacrylonitrile (PAN) nanofibers were stabilized and carbonized to convert them into carbon nanofibers. The diameters of typical carbon nanofibers were in the range from 100 -500 nanometers. Compared to the vapor grown carbon nanofibers, the electronspun carbon nanofibers were continuous, uniform in diameter, and solid. The electrospun nanofiber samples did not require purification. The carbon nanofibers were characterized by scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. Electron and X-ray diffraction patterns were obtained and analyzed. Nanocomposites of epoxy resin reinforced with as-spun PAN and carbon nanofibers were fabricated and analyzed. The results showed good potential of continuous carbon nanofibers for nanocomposite and other applications.

Sign in / Sign up

Export Citation Format

Share Document