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.

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.

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.

X-ray topographic studies of dislocations in iron-silicon alloy single crystals

1965 ◽  
Vol 285 (1401) ◽  
pp. 297-311 ◽  
Keyword(s):  
Single Crystals ◽  
Bulk Material ◽  
Spatial Arrangement ◽  
Atomic Weight ◽  
Thin Plates ◽  
Etch Pits ◽  
Etching Technique ◽  
Dislocation Configuration ◽  
X Ray ◽  
Dislocation Etching

Thin plates cut from melt-grown single crystals of iron +3.5% silicon were examined by an X-ray transmission topographic method and the spatial arrangement of individual dislocations and of dislocation arrays was investigated. The directions (including the sense in some cases) of dislocation Burgers vectors were identified. It was confirmed that Burgers vectors lie along <111>. Reactions such as ½[1̄11] + ½[111̄] = [010] were not observed among the individually resolved dislocations. The minimum separation of dislocations for easy individual resolution was 3 μ m with Co Kα radiation and 5 μ m with Ag Kα . It was demonstrated that a one-to-one correspondence exists between dislocation outcrops and the etch pits produced by the dislocation-etching technique of Šesták (1959). The experiments showed that transmission X-ray topography when applied to metals of moderately heavy atomic weight can give a clear picture of the dislocation configuration in specimens sufficiently thick to be fully representative of the bulk material.

Dislocation Content of Etch Pits in Hexagonal Silicon Carbide

2000 ◽  
Vol 640 ◽  
Author(s):  
Igor I. Khlebnikov ◽  
Mohsen B. Lari ◽  
Yuri I. Khlebnikov ◽  
Robert T. Bondokov ◽  
Ramakrishna Ayyagari ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Crystal Growth ◽  
Growth Process ◽  
Linear Array ◽  
Strong Relationship ◽  
Morphological Features ◽  
Physical Basis ◽  
Etch Pits ◽  
Etch Pit ◽  
Crystal Growth Process

ABSTRACT6H- and 4H- SiC crystals grown on the Si-face were chemically etched on the as-grown (virgin) surface and the C-face (sliced side). The etching of both the surfaces revealed a strong relationship between a variety of etch pits and the morphological features of the grown boule surface. Several types of etched patterns were revealed. On the Si face, we observed small, medium, and large hexagonal shaped pits and a linear array of small etch pits. However, the C face contained only small pits and a linear array of small pits.We observed individual or group of dislocations that were connected from the Si face to the opposite C face of the wafer. Also, etch pit lines oriented along specific crystallographic directions were seen.Our experimental observations have provided a physical basis to explain the generation of defects in SiC. An analysis of our observations show that a correlation exists between the distribution of different size etch pits and the condition of the crystal growth process.

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.

Superscrew dislocation contrast on synchrotron white-beam topographs: an accurate description of the direct dislocation image

1999 ◽  
Vol 32 (3) ◽  
pp. 516-524 ◽  
Author(s):  
X. R. Huang ◽  
M. Dudley ◽  
W. M. Vetter ◽  
W. Huang ◽  
W. Si ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Simulation Model ◽  
Efficient Method ◽  
Dislocation Core ◽  
Crystal Defects ◽  
Formation Mechanisms ◽  
X Ray ◽  
White Beam ◽  
Quantitative Characteristics ◽  
Distorted Region

A kinematic (geometrical) diffraction simulation model has been developed to provide understanding of direct dislocation images on synchrotron white-beam X-ray topographs, and has been successfully applied to illustrate the contrast formation mechanisms involved in images of micropipe-related superscrew dislocations in silicon carbide crystals. The coincidence of the simulations with the contrast features of the superscrew dislocation images, recorded using a series of synchrotron topography techniques, shows that this model is capable of revealing the detailed diffraction behavior of the highly distorted region around the dislocation core and determining the quantitative characteristics of the dislocations. The simulation technique is thus demonstrated to be a simple but efficient method for interpretation of synchrotron topographs, and may be applied to explain the topographic contrast characters of general crystal defects.

AFM Observation of Etch-Pit Shapes on β-Ga2O3 (001) Surface Formed by Molten Alkali Etching

2020 ◽  
Vol 1004 ◽  
pp. 512-518
Author(s):  
Kenichi Ogawa ◽  
Naoya Ogawa ◽  
Ryo Kosaka ◽  
Toshiyuki Isshiki ◽  
Toru Aiso ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Gallium Oxide ◽  
Crystal Defects ◽  
Etch Pits ◽  
Planar Defects ◽  
Etch Pit ◽  
Atomic Force ◽  
Shell Type ◽  
Afm Observation ◽  
Scanning Electron

In order to understand the crystal defects of beta-gallium oxide (β-Ga2O3) in more detail, we classified the crystal defects of a 2-inch substrate of β-Ga2O3 (001) single crystal. As a result of observing the etch pits formed by molten alkali etching using scanning electron microscope (SEM) and atomic force microscope (AFM), we succeeded in observing six different etch pit shapes. These etch pit shapes are categorized into “Cicada I type”, “Cicada II type”, “Cannonball type”, “Trapezoid type”, “Bar type”, and “Shell type”. We consider that “Cicada I type” and “Cicada II type” are etch pit shapes caused by planar defects, and “Cannon ball type” is etch pit shapes due to dislocations. In addition, “Trapezoid type”, “Bar type”, and “Shell type” are deduced the result of surface morphology.

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