White beam X-ray Diffraction Topography (WBXDT) Studies of Bridgman Grown CdZnTe Crystals

2015 ◽  
Vol 1792 ◽  
Author(s):  
Stephen Babalola ◽  
Samuel Uba ◽  
Anwar Hossain ◽  
Giuseppe Camarda ◽  
Ralph James ◽  
...  
Keyword(s):  
Growth Parameters ◽  
Charge Trapping ◽  
Radiation Detectors ◽  
Growth Conditions ◽  
High Energy ◽  
Infrared Transmission ◽  
X Ray Diffraction ◽  
Large Area ◽  
X Ray ◽  
White Beam

ABSTRACTCZT is a semiconductor material that promises to be a good candidate for uncooled gamma radiation detectors. However, to date, we are yet to overcome the technological difficulties in production of large size, defect-free CZT crystals. The most common problem is accumulation of Tellurium precipitates as microscopic inclusions. These inclusions influence the charge collection through charge trapping and electric field distortion. We employed high energy transmission X-ray diffraction techniques to study the quality of the CdZnTe crystals grown by Bridgman Technique. Crystallinity and defects within two different growth set-ups, i.e. with and without choked seeding, were compared by imaging the crystal orientation topography with white beam X-ray diffraction topography (WBXDT). The X-ray diffraction topography results show high correlation with large-area infrared transmission images of the crystals. Grain boundaries that are highly decorated with Te inclusions are observed. Characteristic Te inclusion arrangements as a result of growth conditions are discussed. We also measured the electronic properties of the detectors fabricated from ingots grown using two Bridgman processes, and observed a reduction in electrical resistivity of choked-seeding-grown CdZnTe crystals. Our results show that although choked seeding technique holds a promise in the realization of high quality mono-crystalline CdZnTe, current growth parameters must be improved to obtain defect-free crystals. These results are helpful to attain optimal seeding process for Bridgman-growth of large single crystals of CdZnTe.

Synchrotron white beam x-ray topography (SWBXT) and high resolution triple axis diffraction studies on AlN layers grown on 4H- and 6H-SiC seeds

2004 ◽  
Vol 831 ◽  
Author(s):  
Balaji Raghothamachar ◽  
Michael Dudley ◽  
Rafael Dalmau ◽  
Raoul Schlesser ◽  
Zlatko Sitar
Keyword(s):  
High Resolution ◽  
Single Crystal ◽  
Large Diameter ◽  
Laser Diodes ◽  
Growth Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
White Beam ◽  
Strain Data ◽  
Growth Experiments

ABSTRACTFor nitride based devices such as LEDs, high power FETs and laser diodes, single crystal substrates of AlN are highly desirable. While the sublimation technique is suitable for growing bulk AlN crystals, appropriate seeds are also necessary for growing large diameter oriented boules. 4H- and 6H-SiC substrates which are readily available commercially can potentially be implemented as seeds for bulk AlN growth. However, issues regarding SiC decomposition at high temperatures, thermal expansion mismatch, single crystal growth, etc. need to be addressed. Towards this end, a series of growth experiments have been carried out in a resistively heated reactor using on and off-axis 4H- and 6H-SiC substrates as seeds for AlN growth from the vapor phase. Several hundred microns thick AlN layers have been grown under different growth conditions. Synchrotron white beam x-ray topography (SWBXT) has been used to map the defect distribution in the grown layers and high resolution triple axis x-ray diffraction (HRTXD) experiments were carried out to record reciprocal space maps from which tilt, mismatch and strain data can be obtained. These results are analyzed with respect to the growth conditions in order to gain a better understanding of this growth process.

Drastic Change in the Gan Film Quality by In-Situ Controlling Surface Reconstructions In Gsmbe

1997 ◽  
Vol 482 ◽  
Author(s):  
X. Q. Shen ◽  
S. Tanaka ◽  
S. Iwai ◽  
Y. Aoyagi
Keyword(s):  
Growth Conditions ◽  
High Energy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Gas Source ◽  
Atomic Force ◽  
Surface Reconstructions ◽  
Gan Film

AbstractGaN growth was performed on 6H-SiC (0001) substrates by gas-source molecular beam epitaxy (GSMBE), using ammonia (NH3) as a nitrogen source. Two kinds of reflection high-energy electron diffraction (RHEED) patterns, named (1×1) and (2×2), were observed during the GaN growth depending on the growth conditions. By careful RHEED study, it was verified that the (1×1) pattern was corresponded to a H2-related nitrogen-rich surface, while (2×2) pattern was resulted from a Ga-rich surface. By x-ray diffraction (XRD), photoluminescence (PL) and atomic force microscopy (AFM) characterizations, it was found that the GaN quality changed drastically grown under different RHEED patterns. GaN film grown under the (1×1) RHEED pattern showed much better qualities than that grown under the (2×2) one.

scholarly journals High energy white beam x-ray diffraction studies of residual strains in engineering components

2008 ◽  
Author(s):  
S. Y. Zhang ◽  
W. Vorster ◽  
T. S. Jun ◽  
X. Song ◽  
M. Golshan ◽  
...  
Keyword(s):  
High Energy ◽  
X Ray Diffraction ◽  
X Ray ◽  
White Beam ◽  
Residual Strains

Selective Area Heteroepitaxy of Nano-AlGaN UV Excitation Sources for Biofluorescence Application

2006 ◽  
Vol 916 ◽  
Author(s):  
Vibhu Jindal ◽  
James Grandusky ◽  
Fatemeh Shahedipour-Sandvik ◽  
Steven LeBoeuf ◽  
Joleyn Balch ◽  
...  
Keyword(s):  
Growth Rate ◽  
Growth Parameters ◽  
Growth Conditions ◽  
X Ray Diffraction ◽  
High Quality ◽  
X Ray ◽  
Selective Area ◽  
Mask Material ◽  
Uv Excitation ◽  
Selection Of

AbstractWe report on the selective area heteroepitaxy and facet evolution of AlGaN nanostructures on GaN/sapphire substrate using various mask materials. We also report on the challenges associated with selection of an appropriate mask material for selective area heteroepitaxy of AlGaN with varying Al composition. The shape and the growth rate of the nanostructures are observed to be greatly affected by the mask material. The evolution of the AlGaN nanostructures and Al incorporation were studied exhaustively as a function of growth parameters; including temperature, pressure, NH3 flow, total alkyl flow and TMAl/(TMAl+TMGa) ratio. The growth rate of nanostructures was reduced drastically when higher Al percentage AlGaN nanostructures were grown. The growth rates were increased for higher Al percentage AlGaN using a surfactant which resulted in a high quality pyramidal structure. As indicated by high resolution x-ray diffraction (XRD) and cathodoluminescence (CL) spectroscopy, composition of Al in the AlGaN nanostructure is significantly different from that of a thin film grown under the same growth conditions.

Selective area heteroepitaxy of nano-AlGaN ultraviolet excitation sources for biofluorescence application

2007 ◽  
Vol 22 (4) ◽  
pp. 838-844 ◽  
Author(s):  
Vibhu Jindal ◽  
James R. Grandusky ◽  
Neeraj Tripathi ◽  
Fatemeh Shahedipour-Sandvik ◽  
Steven LeBoeuf ◽  
...  
Keyword(s):  
Growth Rate ◽  
Growth Parameters ◽  
Growth Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ultraviolet Excitation ◽  
Selective Area ◽  
Cathodoluminescence Spectroscopy ◽  
Mask Material ◽  
Selection Of

We report on the selective area heteroepitaxy and facet evolution of AlGaN nanostructures on GaN/sapphire substrate using various mask materials. We also report on the challenges associated with selection of an appropriate mask material for selective area heteroepitaxy of AlGaN with varying Al composition. The shape and the growth rate of the nanostructures are observed to be greatly affected by the mask material. The evolution of the AlGaN nanostructures and Al incorporation were studied exhaustively as a function of growth parameters including temperature, pressure, NH3 flow, total alkyl flow, and TMAl/(TMAl+TMGa) ratio. The growth rate of nanostructures was reduced drastically when higher Al percentage AlGaN nanostructures were grown. The growth rates were increased for higher Al percentage AlGaN using a surfactant, which resulted in a high-quality pyramidal structure. As indicated by high-resolution x-ray diffraction and cathodoluminescence spectroscopy, the composition of Al in the AlGaN nanostructure is significantly different from that of a thin film grown under the same growth conditions.

Determination of directionally dependent structural and microstructural information using high-energy X-ray diffraction

2008 ◽  
Vol 41 (6) ◽  
pp. 1109-1114 ◽  
Author(s):  
J. E. Daniels
Keyword(s):  
Zirconium Alloys ◽  
High Energy ◽  
Ferroelectric Ceramics ◽  
X Ray Diffraction ◽  
Large Area ◽  
X Ray ◽  
Area Detector ◽  
Profile Fitting ◽  
Multiple Data Sets ◽  
Dependent Sample

High-energy synchrotron X-ray diffraction using a monochromatic beam and large area detector offers a unique method for the study of directionally dependent sample information. The very short wavelengths and subsequent low scattering angles mean that scattering vectors at all angles approximately perpendicular to the beam direction are sampled simultaneously. Here a method is proposed and demonstrated in which the magnitude and directions of structural and microstructural changes can be determined with higher resolution than was possible with previously used techniques. The method takes advantage of parametric refinements over multiple data sets using the profile fitting packageTOPAS. Examples of the technique applied to the study of strains in multiphase zirconium alloys and microstructural texture in ferroelastic/ferroelectric ceramics are given. The angular precision in lattice strain for a diffraction image with good statistics is found to be below 0.1°.

Evaluation of an alternative technique for the fabrication of direct detector X-ray imagers: spray pyrolysis of lead iodide and mercury iodide

2004 ◽  
Vol 808 ◽  
Author(s):  
J. F. Condeles ◽  
J. C. Ugucioni ◽  
M. Mulato
Keyword(s):  
Thin Films ◽  
Spray Pyrolysis ◽  
Deposition Process ◽  
Radiation Detectors ◽  
Deposition Technique ◽  
X Ray Diffraction ◽  
Large Area ◽  
Lead Iodide ◽  
X Ray ◽  
Mercury Iodide

ABSTRACTThis work discusses the new use of an old deposition technique: spray pyrolysis. The objective is the deposition of thin films of lead iodide and mercury iodide and their future use as photoconductors in medical X-ray digital imagers. We discuss the main advantages and limitations of the deposition process comparing both materials. The final thin films are structurally investigated using X-ray diffraction and microscopy. The deposition technique seems to be very promising for the future development of large area radiation detectors.

Effect of Growth Conditions and Buffer Layers on the Metal-Insulator Transition in V2O3 Thin Films

1995 ◽  
Vol 401 ◽  
Author(s):  
H. Schuler ◽  
G. Weissmann ◽  
C. Renner ◽  
S. Six ◽  
S. Klimm ◽  
...  
Keyword(s):  
Thin Films ◽  
Growth Conditions ◽  
Buffer Layers ◽  
Infrared Transmission ◽  
X Ray Diffraction ◽  
Metal Insulator ◽  
X Ray ◽  
Sapphire Substrates ◽  
Hall Effect Measurements ◽  
Mi Transition

AbstractThin films of V2O3 with thickness from 20 to 450 nm were deposited on (0001) oriented sapphire substrates by reactive e-beam evaporation. LEED, x-ray diffraction and AFM studies show highly oriented grains with a lateral size of 50 to 800 nm, dependent on substrate temperature and deposition rate. The films were characterized by optical and infrared transmission, electrical resistance and Hall effect measurements. Films grown directly on the Al2O3-substrate show a very broad metal-insulator (MI) transition as a function of temperature. The width of the transition decreases with increasing film thickness. The insertion of Cr2O3 buffer layers decreases the transition width by a further factor of three. The electronic properties of the films can be drastically influenced by the growth conditions.

Characterizations of Synthetic 8mol% YSZ with Comparison to 3mol %YSZ for HT-SOFC

2020 ◽  
Vol 38 (4A) ◽  
pp. 491-500
Author(s):  
Abeer F. Al-Attar ◽  
Saad B. H. Farid ◽  
Fadhil A. Hashim
Keyword(s):  
Ionic Conductivity ◽  
Electrochemical Impedance ◽  
Structural Information ◽  
Impedance Analysis ◽  
High Energy ◽  
Yttria Stabilized Zirconia ◽  
X Ray Diffraction ◽  
Stabilized Zirconia ◽  
Powder Morphology ◽  
X Ray

In this work, Yttria (Y2O3) was successfully doped into tetragonal 3mol% yttria stabilized Zirconia (3YSZ) by high energy-mechanical milling to synthesize 8mol% yttria stabilized Zirconia (8YSZ) used as an electrolyte for high temperature solid oxide fuel cells (HT-SOFC). This work aims to evaluate the densification and ionic conductivity of the sintered electrolytes at 1650°C. The bulk density was measured according to ASTM C373-17. The powder morphology and the microstructure of the sintered electrolytes were analyzed via Field Emission Scanning Electron Microscopy (FESEM). The chemical analysis was obtained with Energy-dispersive X-ray spectroscopy (EDS). Also, X-ray diffraction (XRD) was used to obtain structural information of the starting materials and the sintered electrolytes. The ionic conductivity was obtained through electrochemical impedance spectroscopy (EIS) in the air as a function of temperatures at a frequency range of 100(mHz)-100(kHz). It is found that the 3YSZ has a higher density than the 8YSZ. The impedance analysis showed that the ionic conductivity of the prepared 8YSZ at 800°C is0.906 (S.cm) and it was 0.214(S.cm) of the 3YSZ. Besides, 8YSZ has a lower activation energy 0.774(eV) than that of the 3YSZ 0.901(eV). Thus, the prepared 8YSZ can be nominated as an electrolyte for the HT-SOFC.

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