Threading dislocation classification for 4H-SiC substrates using the KOH etching method

CrystEngComm ◽  
2018 ◽  
Vol 20 (7) ◽  
pp. 978-982 ◽  
Author(s):  
Yingxin Cui ◽  
Xiaobo Hu ◽  
Xuejian Xie ◽  
Xiangang Xu
Keyword(s):  
Selective Etching ◽  
Threading Dislocation ◽  
Threading Dislocations ◽  
Etching Method ◽  
Koh Etching

We have studied the threading dislocations of 4H-SiC substrates with different conductivity types by means of molten KOH defect selective etching.

Defect Revelation and Evaluation of 4H Silicon Carbide by Optimized Molten KOH Etching Method

2013 ◽  
Vol 740-742 ◽  
pp. 243-246 ◽  
Author(s):  
Lin Dong ◽  
Liu Zheng ◽  
Xing Fang Liu ◽  
Feng Zhang ◽  
Guo Guo Yan ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Statistical Data ◽  
Structural Features ◽  
Selective Etching ◽  
Etching Method ◽  
Dislocation Densities ◽  
Morphological Defects ◽  
Koh Etching ◽  
Insulating Substrates

We have studied the defects on 4H-SiC substrates and epilayers by using molten KOH defect selective etching. It is found that adding Na2O2 into molten KOH at the etched temperature enables the revelation of dislocations on n+ and semi-insulating substrates, whereas purely molten KOH is sufficient to obtain good etched pattern on p+ substrates. Related statistical data on dislocation densities of n+, p+ and semi-insulating substrates are also presented. The morphological defects commonly observed on the epilayers are finally investigated and it is shown that some important structural features can be revealed by molten KOH method.

Threading Dislocation Density Reduction in GaN/Sapphire Heterostructures.

1999 ◽  
Vol 595 ◽  
Author(s):  
A. Kvit ◽  
A. K. Sharma ◽  
J. Narayan
Keyword(s):  
Basal Plane ◽  
Stacking Faults ◽  
High Density ◽  
Thin Layers ◽  
Interfacial Region ◽  
Threading Dislocation ◽  
Threading Dislocations ◽  
Misfit Dislocations ◽  
Plan View ◽  
Partial Dislocations

AbstractLarge lattice mismatch between GaN and α-Al2O3 (15%) leads to the possibility of high threading dislocation densities in the nitride layers grown on sapphire. This investigation focused on defect reduction in GaN epitaxial thin layer was investigated as a function of processing variables. The microstructure changes from threading dislocations normal to the basal plane to stacking faults in the basal plane. The plan-view TEM and the corresponding selected-area diffraction patterns show that the film is single crystal and is aligned with a fixed epitaxial orientation to the substrate. The epitaxial relationship was found to be (0001)GaN∥(0001)Sap and [01-10]GaN∥[-12-10]Sap. This is equivalent to a 30° rotation in the basal (0001) plane. The film is found to contain a high density of stacking faults with average spacing 15 nm terminated by partial dislocations. The density of partial dislocations was estimated from plan-view TEM image to be 7×109 cm−2. The cross-section image of GaN film shows the density of stacking faults is highest in the vicinity of the interface and decreases markedly near the top of the layer. Inverted domain boundaries, which are almost perpendicular to the film surface, are also visible. The concentration of threading dislocation is relatively low (∼;2×108 cm−2), compared to misfit dislocations. The average distance between misfit dislocations was found to be 22 Å. Contrast modulations due to the strain near misfit dislocations are seen in high-resolution cross-sectional TCM micrograph of GaN/α-Al2O3 interface. This interface is sharp and does not contain any transitional layer. The interfacial region has a high density of Shockley and Frank partial dislocations. Mechanism of accommodation of tensile, sequence and tilt disorder through partial dislocation generation is discussed. In order to achieve low concentration of threading dislocations we need to establish favorable conditions for some stacking disorder in thin layers above the film-substrate interface region.

Revealing of dislocations in diamond crystals by the selective etching method

2006 ◽  
Vol 293 (2) ◽  
pp. 469-474 ◽  
Author(s):  
Alexander F. Khokhryakov ◽  
Yuri N. Palyanov
Keyword(s):  
Selective Etching ◽  
Etching Method ◽  
Diamond Crystals

Nonradiative recombination at threading dislocations in n-type GaN: Studied by cathodoluminescence and defect selective etching

2008 ◽  
Vol 92 (23) ◽  
pp. 231909 ◽  
Author(s):  
M. Albrecht ◽  
J. L. Weyher ◽  
B. Lucznik ◽  
I. Grzegory ◽  
S. Porowski
Keyword(s):  
Selective Etching ◽  
Threading Dislocations ◽  
Nonradiative Recombination

scholarly journals The heterogeneous nucleation of threading dislocations on partial dislocations in III-nitride epilayers

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
J. Smalc-Koziorοwska ◽  
J. Moneta ◽  
P. Chatzopoulou ◽  
I. G. Vasileiadis ◽  
C. Bazioti ◽  
...  
Keyword(s):  
Heterogeneous Nucleation ◽  
Physical Mechanism ◽  
Dislocation Nucleation ◽  
Threading Dislocation ◽  
Threading Dislocations ◽  
Physical Mechanisms ◽  
Partial Dislocations ◽  
Transmission Electron ◽  
Device Applications ◽  
Very High

Abstract III-nitride compound semiconductors are breakthrough materials regarding device applications. However, their heterostructures suffer from very high threading dislocation (TD) densities that impair several aspects of their performance. The physical mechanisms leading to TD nucleation in these materials are still not fully elucidated. An overlooked but apparently important mechanism is their heterogeneous nucleation on domains of basal stacking faults (BSFs). Based on experimental observations by transmission electron microscopy, we present a concise model of this phenomenon occurring in III-nitride alloy heterostructures. Such domains comprise overlapping intrinsic I1 BSFs with parallel translation vectors. Overlapping of two BSFs annihilates most of the local elastic strain of their delimiting partial dislocations. What remains combines to yield partial dislocations that are always of screw character. As a result, TD nucleation becomes geometrically necessary, as well as energetically favorable, due to the coexistence of crystallographically equivalent prismatic facets surrounding the BSF domain. The presented model explains all observed BSF domain morphologies, and constitutes a physical mechanism that provides insight regarding dislocation nucleation in wurtzite-structured alloy epilayers.

Nucleation of misfit and threading dislocations in GaSb/GaAs(001) heterostructure

1996 ◽  
Vol 54 ◽  
pp. 946-947
Author(s):  
W. Qian ◽  
M. Skowronski ◽  
R. Kaspi ◽  
M. De Graef
Keyword(s):  
Lattice Mismatch ◽  
Strain Relaxation ◽  
Threading Dislocation ◽  
Threading Dislocations ◽  
Misfit Dislocations ◽  
Extended Defects ◽  
Large Lattice ◽  
Threading Dislocation Density ◽  
Small Lattice ◽  
Large Lattice Mismatch

GaSb thin film grown on GaAs is a promising substrate for fabrication of electronic and optical devices such as infrared photodetectors. However, these two materials exhibit a 7.8% lattice constant mismatch which raises concerns about the amount of extended defects introduced during strain relaxation. It was found that, unlike small lattice mismatched systems such as InxGa1-xAs/GaAs or GexSi1-x/Si(100), the GaSb/GaAs interface consists of a quasi-periodic array of 90° misfit dislocations, and the threading dislocation density is low despite its large lattice mismatch. This paper reports on the initial stages of GaSb growth on GaAs(001) substrates by molecular beam epitaxy (MBE). In particular, we discuss the possible formation mechanism of misfit dislocations at the GaSb/GaAs(001) interface and the origin of threading dislocations in the GaSb epilayer.GaSb thin films with nominal thicknesses of 5 to 100 nm were grown on GaAs(001) by MBE at a growth rate of about 0.8 monolayers per second.

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