New Separation Method of Threading Dislocations in 4H-SiC Epitaxial Layer by Molten KOH Etching

2011 ◽  
Vol 679-680 ◽  
pp. 298-301 ◽  
Author(s):  
T. Katsuno ◽  
Y. Watanabe ◽  
Fujiwara Hirokazu ◽  
Masaki Konishi ◽  
Takeo Yamamoto ◽  
...  
Keyword(s):  
Epitaxial Layer ◽  
Basal Plane ◽  
Separation Method ◽  
New Method ◽  
Threading Dislocations ◽  
Screw Dislocations ◽  
Etch Pit ◽  
Almost All ◽  
Edge Dislocations ◽  
Koh Etching

A new method for the separation of threading screw dislocations (TSD) and threading edge dislocations (TED) in a 4H-SiC epitaxial layer is proposed by measurement of the etch pit angles. The etch pit angles of the TSDs and TEDs were 28±3 and 18±3°, respectively. In the case of etch pit depths within the epitaxial layer, the values were almost constant. Almost all of the TSDs were converted from basal plane dislocations (BPDs) at the epitaxial layer/substrate interface.

Dislocations Propagation Study Trough High-Resolution 4H-SiC Substrate Mapping

2019 ◽  
Vol 963 ◽  
pp. 276-279 ◽  
Author(s):  
Ruggero Anzalone ◽  
Nicolò Piluso ◽  
Andrea Severino ◽  
Simona Lorenti ◽  
Giuseppe Arena ◽  
...  
Keyword(s):  
High Resolution ◽  
Epitaxial Layer ◽  
Basal Plane ◽  
Stacking Faults ◽  
Screw Dislocations ◽  
Density Maps ◽  
Dislocations Density ◽  
Koh Etching

In this work a deep investigation of the dislocation on 4H-SiC substrate has been shown. The dislocation intersecting the surface were enhanced by KOH etching at 500 deg. C. performed on whole 6 inches substrate. A comparison between basal plane dislocations and threading screw dislocations in the substrate with the defects in the epitaxial layer (mainly stacking faults and carrots) was performed. The comparison between shows a correlation between basal plane dislocations density and stacking faults density maps.

Large-Area Mapping of Dislocations in 4H-SiC from Carbon-Face (000-1) by Using Vaporized KOH Etching near 1000 °C

2013 ◽  
Vol 740-742 ◽  
pp. 829-832
Author(s):  
Yong Zhao Yao ◽  
Yukari Ishikawa ◽  
Koji Sato ◽  
Yoshihiro Sugawara ◽  
Katsunori Danno ◽  
...  
Keyword(s):  
Basal Plane ◽  
Chemical Etching ◽  
Sample Thickness ◽  
Large Area ◽  
Inexpensive Method ◽  
Etching Technique ◽  
Screw Dislocations ◽  
Wafer Thickness ◽  
Edge Dislocations ◽  
Koh Etching

To solve the problem that no preferential chemical etching is available for dislocation revelation from the carbon-face (C-face) of 4H-SiC, a novel etching technique using vaporized KOH has been developed. It was found that this etching technique can reveal the three commonly found dislocation types, i.e., threading screw dislocations (TSDs), threading edge dislocations (TEDs) and basal plane dislocations (BPDs) as large hexagonal, small hexagonal and triangular, respectively. Centimeter-scale dislocation mapping has been obtained, and the pit positions on the C-face were compared with those on the Si-face, to study the dislocation propagation behaviors across the sample thickness. We have found one-to-one correlation for nearly 96% of the TSDs, indicating a dominant proportion of TSDs penetrate the whole wafer thickness. The vaporized KOH etching technique has provided an effective and inexpensive method of making inch-scale mapping of dislocation distribution for the C-face epitaxial and bulky 4H-SiC.

Effect of Surface Polarity on the Conversion of Threading Dislocations in Solution Growth

2013 ◽  
Vol 740-742 ◽  
pp. 15-18 ◽  
Author(s):  
Yuji Yamamoto ◽  
S. Harada ◽  
Kazuaki Seki ◽  
Atsushi Horio ◽  
Takato Mitsuhashi ◽  
...  
Keyword(s):  
Grown Crystal ◽  
The Other ◽  
Solution Growth ◽  
Threading Dislocations ◽  
Surface Polarity ◽  
Screw Dislocations ◽  
X Ray ◽  
Almost All ◽  
Edge Dislocations ◽  
Effect Of Surface

We investigated the dislocation behaviors during the solution growth on Si-face and C-face off-axis 4H-SiC seed crystals by using synchrotron X-ray topography. On Si-face, almost all threading screw dislocations (TSDs) and threading edge dislocations (TEDs) are converted into Frank-type defects and basal plane dislocations (BPDs), respectively. On the other hand, on C-face, TSDs were hardly converted. Some of TEDs were converted to BPDs and BPD-TED reconversion was often occurred. Therefore, to reduce density of threading dislocations in the grown crystal, it is better to use Si-face off-axis seed crystal.

Dislocation Revelation in Highly Doped N-Type 4H-SiC by Molten KOH Etching with Na2O2 Additive

2011 ◽  
Vol 679-680 ◽  
pp. 290-293 ◽  
Author(s):  
Yong Zhao Yao ◽  
Yukari Ishikawa ◽  
Yoshihiro Sugawara ◽  
Hiroaki Saitoh ◽  
Katsunori Danno ◽  
...  
Keyword(s):  
Electron Concentration ◽  
Basal Plane ◽  
Wet Etching ◽  
Etch Pits ◽  
Screw Dislocations ◽  
Edge Dislocations ◽  
Koh Etching

We have proposed a new wet etching recipe using molten KOH and Na2O2 as the etchant (“KN etching”) for dislocation revelation in highly doped n-type 4H-SiC (n+-4H-SiC). Threading screw dislocations (TSDs) and threading edge dislocations (TEDs) have been clearly revealed as hexagonal etch pits differing in pit sizes, and basal plane dislocations (BPDs) as seashell-shaped pits. This new etching recipe has provided a solution to the problem that conventional KOH etching is not effective for dislocation identification in 4H-SiC if the electron concentration is high (>mid-1018 cm-3). We have investigated the effect of SiC off-cut angle on KN etching and it has been shown that the “KN etching” is applicable for the n+-SiC substrate with off-angle from 0o to 8o.

Investigation of In-Grown Dislocations in 4H-SiC Epitaxial Layers

2006 ◽  
Vol 527-529 ◽  
pp. 147-152 ◽  
Author(s):  
Kazutoshi Kojima ◽  
Tomohisa Kato ◽  
Satoshi Kuroda ◽  
Hajime Okumura ◽  
Kazuo Arai
Keyword(s):  
Epitaxial Growth ◽  
Epitaxial Layer ◽  
Basal Plane ◽  
Growth Conditions ◽  
Epitaxial Layers ◽  
Etch Pit Density ◽  
High Conversion Efficiency ◽  
Etch Pit ◽  
Edge Dislocations

We have investigated the generation of new dislocations during the epitaxial growth of 4H-SiC layers. Dislocations were mainly propagated from the substrate into the epitaxial layer. However, it was found that some amount of new threading edge dislocations (TEDs) and basal plane dislocations (BPDs) were generated during the epitaxial growth. The generation of those dislocations appeared to depend on the in-situ H2 etching conditions, not the epitaxial growth conditions. By optimizing in-situ H2 etching condition, we were able to effectively suppress the generation of new dislocations during epitaxial growth, and obtain 4H-SiC epitaxial layers which have the equivalent etch pit density (EPD) to the substrates. Our additional investigation of the conversion of BPDs to TEDs revealed that its efficiency similarly depends on in-situ H2 etching. We were able to obtain a high conversion efficiency of 97 % by optimizing the in-situ H2 etching conditions before epitaxial growth.

Effects of Different Defect Types on the Performance of Devices Fabricated on a 4H-SiC Homoepitaxial Layer

2006 ◽  
Vol 911 ◽  
Author(s):  
Hui Chen ◽  
Balaji Raghothamachar ◽  
William Vetter ◽  
Michael Dudley ◽  
Y. Wang ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Basal Plane ◽  
Schottky Contacts ◽  
Device Performance ◽  
Hollow Core ◽  
Screw Dislocations ◽  
Burgers Vector ◽  
Edge Dislocations ◽  
Sic Wafer ◽  
Koh Etching

AbstractAn 8° off-axis 4H-SiC wafer with circular Schottky contacts fabricated on a CVD grown 4H-SiC homoepitaxial layer was studied to investigate the influence of various defects, including small (closed-core) screw dislocations (Burgers vector of 1c or 2c), hollow-core (micropipes; Burgers vector larger than 2c), threading edge dislocations (from conversion of basal plane dislocations from the substrate into the epilayer), grain boundaries and triangular defects, on the device performance in the form of breakdown voltages. The defects were examined using synchrotron white beam x-ray topography (SWBXT) based techniques and molten KOH etching. The devices commonly contained basal plane dislocations, small screw dislocations and threading edge dislocations, the latter two of which could give rise to low breakdown voltages for the devices. In addition, less commonly observed defects such as micropipes, grain boundaries and triangular defects are much more destructive to device performance than closed-core screw dislocations and threading edge dislocations.

Why Are Only Some Basal Plane Dislocations Converted to Threading Edge Dislocations During SiC Epitaxy?

2006 ◽  
Vol 527-529 ◽  
pp. 419-422 ◽  
Author(s):  
Ze Hong Zhang ◽  
Amitesh Shrivastava ◽  
Tangali S. Sudarshan
Keyword(s):  
Basal Plane ◽  
Reactive Ion Etching ◽  
New Method ◽  
Ion Etching ◽  
Edge Dislocations ◽  
Koh Etching

Dislocations were tracked from 4H-SiC epilayer to the substrate by a new method based on combination of molten KOH etching and Reactive Ion Etching. It was found that basal plane dislocations (BPDs) with dislocation lines parallel (or approximately parallel) to the off-cut direction might propagate as BPDs into the epilayer, while those with dislocation lines forming large angles (>10º) with the off-cut direction will get converted to threading edge dislocations (TEDs). A model is proposed to explain the observations.

Investigation of Low Angle Grain Boundaries in Hexagonal Silicon Carbide

2006 ◽  
Vol 955 ◽  
Author(s):  
Yi Chen ◽  
Hui Chen ◽  
Ning Zhang ◽  
Michael Dudley ◽  
Ronghui Ma
Keyword(s):  
Silicon Carbide ◽  
Grain Boundaries ◽  
Basal Plane ◽  
Vapor Transport ◽  
Threading Dislocations ◽  
Prismatic Plane ◽  
Screw Dislocations ◽  
X Ray ◽  
Edge Dislocations ◽  
Dislocation Walls

ABSTRACTInteraction between basal plane dislocations and single or well-spaced threading dislocations is discussed based on synchrotron white beam X-ray topographic studies carried out on physical vapor transport grown hexagonal silicon carbide single crystals. The basal plane dislocations are able to cut through single or well-spaced threading edge dislocations even if the formation of kinks/jogs is energetically unfavorable while threading screw dislocations were mostly observed to act as effective pinning points. However, basal plane dislocations can sometimes cut through a threading screw dislocation, forming a superjog and which subsequently migrates on the prismatic plane via a cross-slip process. Threading edge dislocation walls act as obstacles for the glide of basal plane dislocations and the mechanism by which this occurs is discussed. The character of low angle grain boundaries and their dislocation content are discussed.

Differences in Emission Spectra of Dislocations in 4H-SiC Epitaxial Layers

2008 ◽  
Vol 600-603 ◽  
pp. 345-348 ◽  
Author(s):  
Kendrick X. Liu ◽  
X. Zhang ◽  
Robert E. Stahlbush ◽  
Marek Skowronski ◽  
Joshua D. Caldwell
Keyword(s):  
Spectral Characteristics ◽  
Emission Spectra ◽  
Spectral Peak ◽  
Epitaxial Layers ◽  
Threading Dislocations ◽  
Screw Dislocations ◽  
Material Defects ◽  
Partial Dislocations ◽  
Edge Dislocations ◽  
Non Destructive

Material defects such as Si-core and C-core partial dislocations (PDs) and threading screw dislocations (TSDs) and threading edge dislocations (TEDs) are being investigated for their contributions to device performances in 4H-SiC. Non-destructive electroluminescence and photoluminescence techniques can be powerful tools for examining these dislocations. In this report, these techniques were used to reveal the different spectral characteristics for the mentioned dislocations. At higher injection levels, both the Si-core and C-core PDs possessed a spectral peak at 700 nm. However, at lower injection levels, the spectral peak for the Si-core PD remained at 700 nm while the peak for the C-core moved to longer wavelengths. For the threading dislocations, TSDs possessed a peak between 800 and 850 nm while the TEDs possessed a peak at 600 nm independent of the injection levels.

Characterization of Basal Plane Dislocations in 4H-SiC Substrates by Topography Analysis of Threading Edge Dislocations in Epilayers

2010 ◽  
Vol 645-648 ◽  
pp. 303-306 ◽  
Author(s):  
Isaho Kamata ◽  
Masahiro Nagano ◽  
Hidekazu Tsuchida
Keyword(s):  
High Resolution ◽  
Epitaxial Layer ◽  
Basal Plane ◽  
Grazing Incidence ◽  
Size Difference ◽  
Etch Pits ◽  
Burgers Vector ◽  
Vector Direction ◽  
Edge Dislocations

Burgers vector directions of threading edge dislocations (TEDs) in 4H-SiC epitaxial layer are distinguished by grazing incidence high resolution topography. Based on comparison between appearance of KOH etch pits and direction of TED Burgers vector, the size difference of the TED etch pits is found to be dependent on their Burgers vector directions. Examining TEDs in the epilayer by topography, the Burgers vector direction of basal plane dislocations (BPDs) in the substrate is identified. Correspondence between the topography contrast and the sense of a BPD is also investigated.

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