Structure and Origin of Carrot Defects on 4H-SiC Homoepitaxial Layers

2014 ◽  
Vol 778-780 ◽  
pp. 354-357 ◽  
Author(s):  
Lin Dong ◽  
Guo Sheng Sun ◽  
Jun Yu ◽  
Guo Guo Yan ◽  
Wan Shun Zhao ◽  
...  
Keyword(s):  
Screw Dislocation ◽  
Basal Plane ◽  
Flow Direction ◽  
Stacking Fault ◽  
Threading Dislocation ◽  
Step Flow ◽  
Homoepitaxial Layers

A kind of broken carrot defects which are not parallel to the step flow direction are observed on 4H-SiC epilayer surfaces. We use the molten KOH and polishing methods to reveal the structure and source of the broken carrots. It is shown that the broken carrot defects still contain the prismatic stacking fault (SF) and basal plane SF and originate from threading screw dislocation on the substrate. The presence of other substrate threading dislocation can disturb the expansion of prismatic SF. This leads to the appearance of the broken carrot.

Investigation of Photoluminescence Emission of Basal Plane Frank-Type Defects in 4H-SiC Epilayers

2011 ◽  
Vol 679-680 ◽  
pp. 310-313
Author(s):  
Isaho Kamata ◽  
Xuan Zhang ◽  
Hidekazu Tsuchida
Keyword(s):  
Optical Properties ◽  
Screw Dislocation ◽  
Basal Plane ◽  
Room Temperature ◽  
Stacking Fault ◽  
Epitaxial Layers ◽  
Photoluminescence Emission ◽  
Pl Emission

Frank-type defects on the basal plane in thick 4H-SiC epitaxial layers converted from threading screw dislocation (TSD) have been characterized by photoluminescence (PL) spectroscopy and PL imaging microscopy. PL emission from the stacking fault (SF) and the Frank partial of the defect was obtained at ~457 nm and >700 nm at room temperature, respectively. The PL emission peaks of two other kinds of Frank-type defects were obtained, and a correspondence between the optical properties and the microscopic structures of the three kinds of defects was clarified.

Conversion Mechanism of Threading Screw Dislocation during SiC Solution Growth

2012 ◽  
Vol 717-720 ◽  
pp. 351-354 ◽  
Author(s):  
Toru Ujihara ◽  
Shigeta Kozawa ◽  
Kazuaki Seki ◽  
Alexander ◽  
Yuji Yamamoto ◽  
...  
Keyword(s):  
Screw Dislocation ◽  
Basal Plane ◽  
Conversion Process ◽  
Solution Growth ◽  
Powerful Method ◽  
High Quality ◽  
X Ray ◽  
Step Flow ◽  
Partial Dislocations ◽  
Step Flow Growth

Solution growth is considered to be a powerful method for high quality SiC crystals. This work reports that the conversion process from a threading screw dislocation into a few Frank partial dislocations in basal planes was investigated by synchrotron X-ray topography. This process was effectively assisted by step-flow growth on off-oriented (0001) seed crystals. The Frank partials were not extended into the crystal grown toward the [0001] direction perpendicular to the basal plane. Thus, the conclusion of this study suggests the use of off-oriented seed crystal is important to improve crystal quality.

Improvement of Surface Morphology by Solution Flow Control in Solution Growth of SiC on Off-Axis Seeds

2015 ◽  
Vol 821-823 ◽  
pp. 31-34 ◽  
Author(s):  
Tomonori Umezaki ◽  
Daiki Koike ◽  
S. Harada ◽  
Toru Ujihara
Keyword(s):  
Flow Direction ◽  
Seed Crystal ◽  
Solution Growth ◽  
Rotational Axis ◽  
Solution Flow ◽  
Step Flow ◽  
Unidirectional Flow ◽  
Novel Method ◽  
Set Up ◽  
Top Seeded Solution Growth

The solution growth of SiC on an off-axis seed is effective on the reduction of threading dislocations. We proposed a novel method to grow a SiC crystal on an off-axis seed by top-seeded solution growth (TSSG). In our previous study, a unidirectional solution flow above a seed crystal is effective to suppress surface roughness in the growth on the off-axis seed. However, it is difficult to apply the unidirectional flow in an axisymmetric TSSG set-up. In this study, the unidirectional flow could be achieved by shifting the rotational axis away from the center of the seed crystal. As a result, the smooth surface was obtained in the wider area where the solution flow direction was opposite to the step-flow direction.

Understanding the breakdown asymmetry of 4H-SiC power diodes with extended defects at locations along step-flow direction

2020 ◽  
Vol 128 (16) ◽  
pp. 164501
Author(s):  
Hu Long ◽  
Na Ren ◽  
Qing Guo ◽  
Xinhui Gan ◽  
Lei Chen ◽  
...  
Keyword(s):  
Flow Direction ◽  
Extended Defects ◽  
Step Flow ◽  
Power Diodes

Annealing Behavior of Electrical Resistivities Perpendicular and Parallel to the Basal Plane of Heavily Nitrogen-Doped 4H-SiC Crystals

2018 ◽  
Vol 924 ◽  
pp. 293-296 ◽  
Author(s):  
Kiyo Okawa ◽  
Yuina Mannen ◽  
Kentaro Shioura ◽  
Noboru Ohtani ◽  
Masakazu Katsuno ◽  
...  
Keyword(s):  
High Temperature ◽  
Basal Plane ◽  
Stacking Fault ◽  
High Temperature Annealing ◽  
Annealing Behavior ◽  
Nitrogen Doped ◽  
Electrical Resistivities ◽  
C 30 ◽  
Induced Changes

The annealing behavior of electrical resistivities perpendicular and parallel to the basal plane of heavily nitrogen-doped 4H-SiC crystals was investigated. The temperature dependencies of the resistivities exhibited characteristic behaviors after multiple rounds of high-temperature annealing (1100°C, 30 min). High-temperature annealing induced stacking fault formation to various extents in heavily nitrogen-doped 4H-SiC crystals. Based on these results, we discuss the cause and mechanism of the observed annealing-induced changes in electrical resistivities of the crystals.

Tem Characterization of ZnO and AIN/ZnO Thin Films Grown on Sapphire

1998 ◽  
Vol 526 ◽  
Author(s):  
K. Dovidenko ◽  
S. Oktyabrsky ◽  
A. K. Sharma ◽  
J. Narayan
Keyword(s):  
Single Crystal ◽  
Pulsed Laser Deposition ◽  
Basal Plane ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Zno Films ◽  
Threading Dislocation ◽  
Epitaxial Relationship ◽  
Spinel Layer ◽  
Plan View

AbstractThin (~ 250 nm) films of ZnO grown by pulsed laser deposition on basal plane of sapphire were studied by transmission electron microscopy (TEM). Plan-view TEM study proved the films to be single crystal with the following epitaxial relationship with the substrate: (0001)znO || (0001)sap with the 30 30° in-plane rotation - [0110]ZnO || [1210]sap. Dislocations lying mostly in basal plane of ZnO and aligned along both <:1010> and <1120> directions having b=1/3[1120] were found. ZnO films were found to have layered growth morphology contrary to columnar morphology of III-nitrides. Consequently, the threading dislocation density in ZnO films (opposing to the AIN and GaN) drops very fast with the thickness: down to 107cm-2 at ~ 250 nm. The effect of post-annealing (which caused significant improvement in electrical and optical properties) on the microstructure of ZnO films was also studied. Contrary to the atomically sharp and clean interface in the as-deposited films, the post-annealed ZnO/sapphire interface contained reacted layer of 30 - 60 A thickness. The structure of the interlayer was determined to be ZnAl2O4 (spinel). The formation of this single crystal spinel layer did not cause deterioration of the ZnO film structure or properties. We have also explored the possibilities of using ZnO as a buffer for III-nitride growth. The epitaxial AIN films were grown on top of the ZnO layer by pulsed laser deposition. Thin (20 -60 A) interfacial reaction layer (also spinel ZnAm2O4) was observed between AIN and ZnO. Formation of this interlayer is studied in conjunction with the AIN epitaxy and the characteristics of defects and interfaces.

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.

Temperature Dependent Stability of Stacking Fault in Highly Nitrogen-Doped 4H-SiC Crystals

2016 ◽  
Vol 858 ◽  
pp. 109-112
Author(s):  
Chisato Taniguchi ◽  
Aiko Ichimura ◽  
Noboru Ohtani ◽  
Masakazu Katsuno ◽  
Tatsuo Fujimoto ◽  
...  
Keyword(s):  
Theoretical Model ◽  
Quantum Well ◽  
Double Layer ◽  
Basal Plane ◽  
Stacking Faults ◽  
Stacking Fault ◽  
Carrier Distribution ◽  
Temperature Dependent ◽  
Nitrogen Doped ◽  
Proposed Model

The formation of basal plane stacking faults in highly nitrogen-doped 4H-SiC crystals was theoretically investigated. A novel theoretical model based on the so-called quantum well action (QWA) mechanism was proposed; the model considers several factors, which were overlooked in a previously proposed model, and explains well the annealing-induced formation of double layer Shockley-type stacking faults in highly nitrogen-doped 4H-SiC crystals. We further revised the model to consider the carrier distribution in the depletion regions adjacent to the stacking fault and were successful in explaining the shrinkage of stacking faults during annealing at even higher temperatures.

Mechanisms of Stacking Fault Growth in SiC PiN Diodes

2004 ◽  
Vol 815 ◽  
Author(s):  
R. E. Stahlbush ◽  
M. E. Twigg ◽  
J. J. Sumakeris ◽  
K. G. Irvine ◽  
P. A. Losee
Keyword(s):  
Basal Plane ◽  
Stacking Faults ◽  
Stacking Fault ◽  
Drift Region ◽  
Pin Diodes ◽  
Current Time ◽  
Partial Dislocations ◽  
Initial Evolution ◽  
A Chain ◽  
Fault Growth

AbstractThe early development of stacking faults in SiC PiN diodes fabricated on 8° off c-axis 4H wafers has been studied. The 150μm drift region and p-n junction were epitaxially grown. The initial evolution of the stacking faults was examined by low injection electroluminescence using current-time product steps as low as 0.05 coul/cm2. The properties of the dislocations present before electrical stressing were determined based on previously observed differences of Si-core and C-core partial dislocations and the patterns of stacking fault expansion. The initial stacking fault expansion often forms a chain of equilateral triangles and at higher currents and/or longer times these triangles coalesce. All of the faulting examined in this paper originated between 10 and 40 μm below the SiC surface. The expansion rate of the bounding partial dislocations is very sensitive to the partials' line directions, their core types and the density of kinks. From these patterns it is concluded that the stacking faults originate from edge-like basal plane dislocations that have Burgers vectors either parallel or anti-parallel to the off-cut direction. Evidence for dislocation conversions between basal-plane and threading throughout the epitaxial drift region is also presented.

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