Defect-Selective Etching of Icosahedral Boron Arsenide (B12As2) Crystals in Molten Potassium Hydroxide

2011 ◽  
Vol 1307 ◽  
Author(s):  
C.E. Whiteley ◽  
A. Mayo ◽  
J.H. Edgar ◽  
M. Dudley ◽  
Y. Zhang
Keyword(s):  
Potassium Hydroxide ◽  
High Energy ◽  
Selective Etching ◽  
Etch Pits ◽  
X Ray ◽  
Etch Pit ◽  
Dislocation Densities ◽  
Boron Arsenide ◽  
Defect Densities ◽  
Molten Nickel

ABSTRACTThe present work reports on the defect-selective etching (DSE) for estimating dislocation densities in icosahedral boron arsenide (B12As2) crystals using molten potassium hydroxide (KOH). DSE takes advantage of the greater reactivity of high-energy sites surrounding a dislocation, compared to the surrounding dislocation-free regions. The etch pits per area are indicative of the defect densities in the crystals, as confirmed by x-ray topography (XRT). Etch pit densities were determined for icosahedral boron arsenide crystals produced from a molten nickel flux as a function of etch time (1-5 minutes) and temperature (400-700°C). The etch pits were predominately triangle shaped, and ranged in size from 5-25μm. The average etch pit density of the triangle and oval etch-pits was on the order of 5x107cm-2 and 3x106cm-2 (respectively), for crystals that were etched for two minutes at 550°C.

Solution Growth and Characterization of Icosahedral Boron Arsenide (B12As2)

2011 ◽  
Vol 1307 ◽  
Author(s):  
C.E. Whiteley ◽  
Y. Zhang ◽  
A. Mayo ◽  
J.H. Edgar ◽  
Y. Gong ◽  
...  
Keyword(s):  
Room Temperature ◽  
Solution Growth ◽  
High Quality ◽  
Burgers Vector ◽  
X Ray ◽  
Dislocation Densities ◽  
Boron Arsenide ◽  
Viable Method ◽  
Molten Nickel

ABSTRACTThe crystallographic properties of bulk icosahedral boron arsenide (B12As2) crystals grown by precipitation from molten nickel solutions were characterized. Large crystals (5-8 mm) were produced by dissolving the boron in nickel at 1150°C for 48-72 hours, reacting with arsenic vapor, and slowly cooling to room temperature. The crystals varied in color from black and opaque to clear and transparent. Raman spectroscopy, x-ray topography (XRT), and defect selective etching revealed that the B12As2 single crystals were high quality with low dislocation densities. Furthermore, XRT results suggest that the major face of the plate-like crystals was (111) type, while (100), (010) and (001) type facets were also observed optically. The predominant defect in these crystals was edge character growth dislocations with a <001> Burgers vector, and <-110> line direction. In short, XRT characterization shows that solution growth is a viable method for producing good quality B12As2 crystals.

Growth of Boron Carbide Crystals from a Copper Flux

2009 ◽  
Vol 1164 ◽  
Author(s):  
Yi Zhang ◽  
James Edgar ◽  
Jack Plummer ◽  
Clinton Whiteley ◽  
Hui Chen ◽  
...  
Keyword(s):  
Boron Carbide ◽  
Potassium Hydroxide ◽  
Crystal Size ◽  
Optical Microscope ◽  
Etch Pit Density ◽  
Bulk Crystals ◽  
Limited Growth ◽  
Etch Pits ◽  
X Ray ◽  
Etch Pit

AbstractBoron carbide crystals ranging in size from 50 microns to several millimeters have been grown from a copper-boron carbide flux at temperatures from 1500°C to 1750°C. The crystal size increased with growth temperature although copper evaporation limited growth at the higher temperatures. Synchrotron X-ray Laue patterns were indexed according to (001) orientation boron carbide structure, indicating the bulk crystals were single crystalline with {001} growth facets. Raman spectrum of boron carbide indicates an improved crystal quality compared to the source powder, but peaks of crystals grown from 11B -enriched source shifted to the lower energy by 1-4 cm−1 from literature values, possibly due to the boron isotope dependency. Five fold symmetry defects and twin planes were common as observed by optical microscope and scanning electron microscope. Raindrop shape etch pits were formed after defect selective etching in molten potassium hydroxide at 600°C for 6 minutes. Typically, the etch pit density was on the order of 106/cm2.

Characterization and Mapping of Crystal Defects in Silicon Carbide

2004 ◽  
Vol 815 ◽  
Author(s):  
E. Emorhokpor ◽  
T. Kerr ◽  
I. Zwieback ◽  
W. Elkington ◽  
M. Dudley ◽  
...  
Keyword(s):  
Image Processing ◽  
Silicon Carbide ◽  
Potassium Hydroxide ◽  
Crystal Defects ◽  
Etch Pits ◽  
Accurate Analysis ◽  
Etching Technique ◽  
X Ray ◽  
Etch Pit ◽  
Density Maps

AbstractA method is presented for detecting, counting and mapping micropipes and dislocations in n+, undoped, and semi-insulating Silicon Carbide wafers. The technique is based on etching in molten Potassium Hydroxide (KOH), and it employs image processing that automatically detects etch pits, discriminates between micropipes and dislocations, and generate micropipe and dislocation density maps. We demonstrate a novel way of detecting and mapping dislocations and micropipes in semi-insulating SiC. This is achieved by combining a properly tuned etching technique that reliably produces well defined etch pits with image processing that enables quick and accurate analysis of the etch pit contrast. We show that the results of optical evaluation are close to those obtained using the Synchrotron White Beam X-Ray Topography (SWBXT) technique.

scholarly journals Dislocation densities in a low-carbon steel during martensite transformation determined by in situ high energy X-Ray diffraction

2021 ◽  
Vol 800 ◽  
pp. 140249
Author(s):  
Juan Macchi ◽  
Steve Gaudez ◽  
Guillaume Geandier ◽  
Julien Teixeira ◽  
Sabine Denis ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Martensite Transformation ◽  
Low Carbon Steel ◽  
High Energy ◽  
Low Carbon ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dislocation Densities

Combined Tem and X-Ray Topographic Characterization of InxGa1−xAs/GaAs Strained Layer Systems.

1990 ◽  
Vol 209 ◽  
Author(s):  
Michael Dudley ◽  
Gong-Da Yao ◽  
David Paine ◽  
David Howard ◽  
Robert N. Sacks
Keyword(s):  
Interfacial Dislocation ◽  
X Ray ◽  
Strained Layer ◽  
Dislocation Densities ◽  
Wide Range ◽  
Lift Off ◽  
Depth Sensitivity ◽  
Non Destructive ◽  
Defect Densities

ABSTRACTNovel application of a combination of TEM and non-destructive synchrotron X-ray topography in both Bragg and grazing Bragg-Laue geometries to the characterization of InxGa1−xAs/GaAs strained layer films is reported. Specialized epilayer lift-off procedures enabled TEM characterization of the defect distributions in macroscopic area films, effectively increasing the field of view of the technique by several orders of magnitude. These lateral distributions correlated well with those observed on both Bragg and grazing Bragg- Laue topographs. Grazing Bragg-Laue images also afforded depth sensitivity. Excellent correlations exist between results obtained with all these techniques for systems with a wide range of In concentrations, corresponding to a broad range of interfacial dislocation densities, although only results for x=;0.085 are presented. This work demonstrates that it is possible to bridge the gap that has traditionally existed between the areas of application of these two generic techniques, in terms of both tolerable defect densities and fields of view. This gap also spans the range of defect densities which is of interest in this and other systems.

Growth and Structural Characterization of Znse Single Crystals

1989 ◽  
Vol 152 ◽  
Author(s):  
Elmer E. Anderson ◽  
Hai- Yuin Cheng ◽  
Michael J. Edgell
Keyword(s):  
Single Crystals ◽  
Electron Spectroscopy ◽  
Vapor Transport ◽  
X Ray Diffraction ◽  
Etch Pits ◽  
X Ray ◽  
Etch Pit ◽  
Auger Microscopy ◽  
Transport Method

ABSTRACTSingle crystals of ZnSe have been grown by the physical vapor transport method in sealed quartz ampoules. The largest crystal grown measures 1 cm x 4 mm x 2 mm and required a total growing time of 11 days. Polished wafers cut from the crystals have been etched and examined by optical microscopy, x-ray diffraction, scanning electron microscopy (SEM), Auger electron spectroscopy (AES) and scanning Auger microscopy (SAM). No impurities or unwanted phases were detected, but frequent twinning occurs. Zn-rich {111} faces were identified by SAM. Triangular etch pits are observed on Zn {lll} faces but not on Se faces. Etch pit densities are about 104 per cm2 on slow-cooled samples but are about 100 times greater when cooling is more rapid.

Elementary Screw and Mixed-Type Dislocations in 4H-SiC Characterized by X-Ray Topography Taken with Six Equivalent 11-28 g-Vectors and a Comparison to Etch Pit Evaluation

2017 ◽  
Vol 897 ◽  
pp. 185-188 ◽  
Author(s):  
Yong Zhao Yao ◽  
Yukari Ishikawa ◽  
Yoshihiro Sugawara ◽  
Yumiko Takahashi ◽  
Keiichi Hirano
Keyword(s):  
Chemical Etching ◽  
Mixed Type ◽  
Threading Dislocations ◽  
Etch Pits ◽  
X Ray ◽  
Etch Pit

We have studied threading dislocations (TDs) in 4H-SiC by means of X-ray topography (XRT) taken under 6 equivalent g-vector of 11-28 and two different chemical etching methods. Threading screw and mixed-type dislocations (TSDs and TMDs) can be distinguished and the direction of the a-components of TMDs can be determined by XRT. Efforts have been made to examine if there are features of etch pits that can be used to distinguish TMDs from TSDs.

Dislocation Revelation for 4H-SiC by Using Vaporized NaOH: A Possible Way to Distinguish Edge, Screw and Mixed Threading Dislocations by Etch Pit Method

2014 ◽  
Vol 778-780 ◽  
pp. 346-349 ◽  
Author(s):  
Yong Zhao Yao ◽  
Yukari Ishikawa ◽  
Yoshihiro Sugawara ◽  
Koji Sato ◽  
Katsunori Danno ◽  
...  
Keyword(s):  
Threading Dislocations ◽  
Power Devices ◽  
Etch Pits ◽  
X Ray ◽  
Etch Pit ◽  
Optical Images ◽  
Geometrical Features ◽  
Facet Orientation ◽  
Sic Wafer ◽  
Inexpensive Technique

In this paper, we report a newly developed dislocation-revealing etch pit method for 4H-SiC single crystal, which can distinguish edge (TED, Burgers vector b=a), elementary screw (TSD, b=1c) and mixed (TMD, b=c+a) threading dislocations. In this method, vaporized NaOH gas was used to etch the Si-face of a SiC wafer at substrate temperature around 950 °C. By a side-by-side comparison between the optical images of the etch pits and the X-ray topographic (XRT) images, it has been found that threading dislocations (TDs) in SiC could be revealed as hexagonal etch pits with distinct geometrical features (shape, size and facet orientation) depending on their Burgers vectors. Based on these results, we consider this etch pit method as an easily-operated and inexpensive technique to categorize TDs, and it may help to promote our understanding on the different roles that these types of TDs have played in the performance degradation of SiC power devices.

Dislocations in SiC Revealed by NaOH Vapor Etching and a Comparison with X-Ray Topography Taken with Various g-Vectors

2016 ◽  
Vol 858 ◽  
pp. 389-392 ◽  
Author(s):  
Yong Zhao Yao ◽  
Yukari Ishikawa ◽  
Yoshihiro Sugawara ◽  
Koji Sato ◽  
Katsunori Danno ◽  
...  
Keyword(s):  
Threading Dislocations ◽  
Etch Pits ◽  
Burgers Vector ◽  
Monochromatic Beam ◽  
X Ray ◽  
Etch Pit ◽  
Pit Formation ◽  
Dislocation Behavior ◽  
Koh Etching

Threading dislocations (TDs) in 4H-SiC have been studied by comparing etch pits formed by NaOH vapor etching with results of synchrotron monochromatic-beam X-ray topography (XRT) taken under different g-vectors. Burgers vectors determined based on XRT results were utilized to investigate the etch pit characteristics of edge (TED), screw (TSD) and mixed (Burgers vector b=c+a, TMD) threading dislocations. It has been found that pit formation by NaOH vapor etching was very different to that by conventional molten KOH etching. We discuss the possibility of using NaOH vapor etching to distinguish TMDs from TSDs, and report a variety of characteristic etch pits formed by this method and their correlations to dislocation behavior.

scholarly journals DEFECT SELECTIVE ETCHING OF THICK AlN LAYERS GROWN ON 6H-SIC SEEDS – A TRANSMISSION ELECTRON MICROSCOPY STUDY

2007 ◽  
Vol 1040 ◽  
Author(s):  
Luke Owuor Nyakiti ◽  
Jharna Chaudhuri ◽  
Ed A Kenik ◽  
Peng Lu ◽  
James H Edgar
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Microscopy Study ◽  
Dark Field ◽  
Selective Etching ◽  
Etch Pits ◽  
Etch Pit ◽  
Transmission Electron

AbstractIn the present study, the type and densities of defects in AlN crystals grown on 6H-SiC seeds by the sublimation-recombination method were assessed. The positions of the defects in AlN were first identified by defect selective etching (DSE) in molten NaOH-KOH at 400 °C for 2 minutes. Etching produced pits of three different sizes: 1.77 ìm, 2.35 ìm , and 2.86 ìm. The etch pits were either aligned together forming a sub-grain boundary or randomly distributed. The smaller etch pits were either isolated or associated with larger etch pits. After preparing cross-sections of the pits by the focused ion beam (FIB) technique, transmission electron microscopy (TEM) was performed to determine which dislocation type (edge, mixed or screw) produced a specific etch pit sizes. Preliminary TEM bright field and dark field study using different zone axes and diffraction vectors indicates an edge dislocation with a Burgers vector 1/3 is associated with the smallest etch pit size.

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