Compliant Substrates With an Embedded Twist Boundary

1998 ◽  
Vol 510 ◽  
Author(s):  
Y. H. Lo ◽  
Z. H. Zhu
Keyword(s):  
Thin Layer ◽  
Current Theory ◽  
Threading Dislocation ◽  
Threading Dislocations ◽  
Twist Boundary ◽  
Free Standing ◽  
New Model ◽  
Compliant Substrates ◽  
Threading Dislocation Density ◽  
Average Size

AbstractIn this article, we propose a new model to explain how heteroepitaxial layers grown on a twist-bonded thin layer may have a significantly reduced number of threading dislocations even if the strain in the epitaxial layers is relaxed. We first point out the deficiency in the existing compliant substrate theory by showing that all the synthesized “compliant substrates” fail to behave as “ideal” free-standing templates assumed by the current theory. Our new model is constructed on the base of stress field interactions between the heteroepitaxial layer and the embedded twist boundary. In the new model, the reduction in threading dislocation density originates from the extension of the dislocation half loops due to the effect of misfit dislocation pinning by the twist boundary. When the average size of the dislocation half loops increases substantially from micrometers to millimeters or even to the size of the wafer, the density of threading dislocations drops significantly. This model does not require any “macroscopic” motion between the bonded thin layer and the handle wafer as the current theory does, which makes it more agreeable with the experimental results

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.

Cantilever Epitaxy of GaN on Sapphire: Further Reductions in Dislocation Density

2002 ◽  
Vol 743 ◽  
Author(s):  
D. M. Follstaedt ◽  
P. P. Provencio ◽  
D. D. Koleske ◽  
C. C. Mitchell ◽  
A. A. Allerman ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Dislocation Density ◽  
Threading Dislocation ◽  
Threading Dislocations ◽  
Processing Conditions ◽  
Optimum Growth ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Threading Dislocation Density

ABSTRACTThe density of vertical threading dislocations at the surface of GaN grown on sapphire by cantilever epitaxy has been reduced with two new approaches. First, narrow mesas (<1 μm wide) were used and {11–22} facets formed over them early in growth to redirect dislocations from vertical to horizontal. Cross-sectional transmission electron microscopy was used to demonstrate this redirection and to identify optimum growth and processing conditions. Second, a GaN nuc-leation layer with delayed 3D → 2D growth transition and inherently lower threading dislocation density was adapted to cantilever epitaxy. Several techniques show that a dislocation density of only 2–3×107/cm2 was achieved by combining these two approaches. We also suggest other developments of cantilever epitaxy for reducing dislocations in heteroepitaxial systems.

X-Ray Topography Characterization of Large Diameter AlN Single Crystal Substrates

2020 ◽  
Vol 1004 ◽  
pp. 63-68
Author(s):  
Rafael Dalmau ◽  
Jeffrey Britt ◽  
Hao Yang Fang ◽  
Balaji Raghothamachar ◽  
Michael Dudley ◽  
...  
Keyword(s):  
Single Crystal ◽  
Large Diameter ◽  
Grazing Incidence ◽  
Threading Dislocation ◽  
Threading Dislocations ◽  
X Ray ◽  
Dislocation Densities ◽  
Transmission Geometry ◽  
Threading Dislocation Density

Large diameter aluminum nitride (AlN) substrates, up to 50 mm, were manufactured from single crystal boules grown by physical vapor transport (PVT). Synchrotron-based x-ray topography (XRT) was used to characterize the density, distribution, and type of dislocations. White beam topography images acquired in transmission geometry were used to analyze basal plane dislocations (BPDs) and low angle grain boundaries (LAGBs), while monochromatic beam, grazing incidence images were used to analyze threading dislocations. Boule diameter expansion, without the introduction of LAGBs around the periphery, was shown. A 48 mm substrate with a uniform threading dislocation density below 7.0 x 102 cm-2 and a BPD of 0 cm-2, the lowest dislocation densities reported to date for an AlN single crystal this size, was demonstrated.

Crystalline Quality Evaluation of SiC p/n Column Layers Formed by Trench-Filling-Epitaxial Growth

2020 ◽  
Vol 1004 ◽  
pp. 445-450
Author(s):  
Kohei Adachi ◽  
Ryoji Kosugi ◽  
Shi Yang Ji ◽  
Yasuyuki Kawada ◽  
Hiroyuki Fujisawa ◽  
...  
Keyword(s):  
Dislocation Density ◽  
Epitaxial Growth ◽  
Epitaxial Layer ◽  
Quality Evaluation ◽  
Crystalline Quality ◽  
Threading Dislocation ◽  
Threading Dislocations ◽  
Threading Dislocation Density

We evaluated crystalline quality of SiC p/n column layers over 20 μm thickness formed by trench-filling-epitaxial growth. Although threading dislocation density of trench-filling-epitaxial layer is almost same as flat n-type epitaxial layer, threading dislocations are localized in only trench-filled p-columns. We consider that threading dislocations migrated toward p-columns around trench bottom during trench-filling-epitaxial growth.

scholarly journals Рентгеноструктурный анализ эпитаксиальных слоев со свойствами дислокационного фильтра

2018 ◽  
Vol 44 (13) ◽  
pp. 19
Author(s):  
И.Д. Лошкарев ◽  
А.П. Василенко ◽  
Е.М. Труханов ◽  
А.В. Колесников ◽  
М.О. Петрушков ◽  
...  
Keyword(s):  
Sharp Decrease ◽  
Epitaxial Films ◽  
Threading Dislocation ◽  
Threading Dislocations ◽  
Gaas Film ◽  
Reciprocal Space Mapping ◽  
X Ray ◽  
Threading Dislocation Density ◽  
Small Angle Boundary ◽  
Low Temperature Gaas

AbstractAn approach to instant testing of epitaxial films with a sharp decrease in the threading dislocation density is proposed. High-resolution X-ray diffractometry, including reciprocal space mapping, has been used. The structure of GaAs/Si(001) heterosystems with low-temperature GaAs layers has been analyzed. A decrease in the density of threading dislocations in the GaAs film with the formation of a small-angle boundary has been detected.

TEM characterization of dislocation reduction processes in GaAs/Si

1989 ◽  
Vol 47 ◽  
pp. 590-591
Author(s):  
R.A. Herring ◽  
P.N. Uppal ◽  
S.P. Svensson ◽  
J.S. Ahearn
Keyword(s):  
Lattice Mismatch ◽  
Threading Dislocation ◽  
Threading Dislocations ◽  
Growth Interface ◽  
Dislocation Reduction ◽  
Dislocation Densities ◽  
Threading Dislocation Density ◽  
Interfacial Dislocations ◽  
Strained Layer Superlattices

A high density of interfacial dislocations are needed at the GaAs/Si interface to alleviate the 4% lattice mismatch between GaAs and Si. Some remnant dislocations thread through the epilayer and follow the growth interface. Current growth methods are not able to obtain acceptable threading dislocation densities (104 – 105) for devices. Many methods can be used to reduce the number of threading dislocations which include misorienting the substrate to enhance the slip of dislocations on specific [110]{111} planes, annealing during and after growth, and adding strained layer superlattices (SLS's) to block dislocations. Conventional TEM (CTEM), performed using a JEM 100c, has been used to characterize threading dislocations in the epilayer of a GaAs/Si material where in situ thermal annealing and SLS's force dislocation reactions and thereby reduce the threading dislocation density. Using TEM we have viewed dislocations under many two-beam diffraction conditions and with the help of a stereogram have determined their Burgers vectors (b), line directions (u) and habit planes (R).

Threading Dislocations in S-Graded ZnSxSe1-x/GaAs (001) Metamorphic Buffer Layers

2014 ◽  
Vol 23 (01n02) ◽  
pp. 1420005 ◽  
Author(s):  
Tedi Kujofsa ◽  
John E. Ayers
Keyword(s):  
Dislocation Density ◽  
Buffer Layer ◽  
Lattice Relaxation ◽  
Buffer Layers ◽  
Cumulative Distribution ◽  
Threading Dislocation ◽  
Threading Dislocations ◽  
Modeling Studies ◽  
Threading Dislocation Density ◽  
Dislocation Behavior

Metamorphic semiconductor devices are commonly fabricated with linearly-graded buffer layers, but equilibrium modeling studies suggest that S-graded buffers, following a normal cumulative distribution function, may enable lower threading defect densities. The present work involves a study of threading dislocation density behavior in S-graded ZnS x Se 1-x buffer layers for metamorphic devices on mismatched GaAs (001) substrates using a kinetic model for lattice relaxation and misfit-threading dislocation interactions. The results indicate that optimization of an S-graded buffer layer to minimize the surface threading dislocation density requires adjustment of the standard deviation parameter and cannot be achieved by varying the buffer thickness alone. Furthermore, it is possible to tailor the design of the S-graded buffer layer in such a way that the density of mobile threading dislocations at the surface vanishes. Nonetheless, the threading dislocation behavior in these heterostructures is quite complex, and a full understanding of their behavior will require further experimental and modeling studies.

Dislocation Density Reduction in GaAs Epilayers on Si Using Strained Layer Superlattices

1989 ◽  
Vol 160 ◽  
Author(s):  
S. Sharan ◽  
J. Narayan ◽  
J. C. C. Fan
Keyword(s):  
Dislocation Density ◽  
Defect Density ◽  
Full Potential ◽  
Threading Dislocation ◽  
Threading Dislocations ◽  
Strained Layer ◽  
Density Reduction ◽  
Threading Dislocation Density ◽  
Superlattice Structures ◽  
Strained Layer Superlattices

AbstractDefects such as dislocations and interfaces play a crucial role in the performance of heterostracture devices. The full potential of GaAs on Si heterostructures can only be realized by controlling the defect density. The reduction of threading dislocations by the use of strained layer superlattices has been studied in these heterostructures. Several superlattice structures have been used to reduce the density of threading dislocations in the GaAs epilayer. The use of strained layer superlattices in conjunction with rapid thermal annealing was most effective in reducing threading dislocation density. Transmission electron microscopy has been used to study the dislocation density reduction and the interaction of threading dislocations with the strained layers. A model has been developed based on energy considerations to determine the critical thickness required for the bending of threading dislocations.

Impact of Surface Morphology above Threading Dislocations on Leakage Current in 4H-SiC Diodes

2012 ◽  
Vol 717-720 ◽  
pp. 911-916 ◽  
Author(s):  
Fujiwara Hirokazu ◽  
T. Katsuno ◽  
Tsuyoshi Ishikawa ◽  
H. Naruoka ◽  
Masaki Konishi ◽  
...  
Keyword(s):  
Dislocation Density ◽  
Leakage Current ◽  
Electric Fields ◽  
Schottky Diodes ◽  
Threading Dislocation ◽  
Threading Dislocations ◽  
Nano Scale ◽  
Threading Dislocation Density ◽  
Positive Correlations ◽  
The Impact

The impact of threading dislocation density on the leakage current of reverse IV characteristics in 1.2 kV Schottky barrier diodes (SBDs), junction barrier Schottky diodes (JBSDs), and PN junction diodes (PNDs) was investigated. The leakage current density and threading dislocation density have different positive correlations in each type of diode. For example, the correlation in SBDs is strong, but weak in PNDs. The threading dislocations were found to be in the same location as the current leakage points in the SBDs, but not in the PNDs. Nano-scale inverted cone pits were observed at the Schottky junction interface in SBDs, and it was found that leakage current increases in these diodes due to the concentration of electric fields at the peaks of the pits. These nano-scale pits were also observed directly above threading dislocations. In addition, this study succeeded in reducing the leakage current variation of 200 A-class JBSDs and SBDs by eliminating the nano-scale pits above the threading dislocations. As a result, a theoretical straight-line waveform was achieved.

Dislocations in InAs Epilayers Grown by MBE on GaAs Substrates Under Various Conditions

1998 ◽  
Vol 523 ◽  
Author(s):  
Hongmei Wang ◽  
Yiping Zeng ◽  
Liang Pan ◽  
Hongwei Zhou ◽  
Zhanping Zhu ◽  
...  
Keyword(s):  
Formation Energy ◽  
Molecular Beam ◽  
Transition Process ◽  
Threading Dislocation ◽  
Threading Dislocations ◽  
Misfit Dislocations ◽  
Mode Transition ◽  
Gaas Substrates ◽  
Transmission Electron ◽  
Threading Dislocation Density

AbstractUsing Transmission Electron Microscopy, we studied the misfit and threading dislocations in InAs epilayers. All the samples, with thickness around 0.5μm, were grown on GaAs(001) substrates by molecular beam epitaxy under As-rich or In-rich conditions. The As-rich growth undergoes 2D-3D mode transition process, which was inhibited under In-rich surface. High step formation energy under As-deficient reconstruction inhibits the formation of 3D islands and leads to 2D growth. The mechanism of misfit dislocations formation was different under different growth condition which caused the variation of threading dislocation density in the epilayers.

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