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

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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Defect Reduction in Cd1-xZnxTe Epilayers on GaAs Substrates

MRS Proceedings ◽

10.1557/proc-299-191 ◽

1994 ◽

Vol 299 ◽

Author(s):

Saket Chadda ◽

Kevin Malloy ◽

John Reno

Keyword(s):

Threading Dislocation ◽

Full Width ◽

X Ray Diffraction ◽

Defect Reduction ◽

X Ray ◽

Gaas Substrates ◽

Transmission Electron ◽

Threading Dislocation Density ◽

Optimum Period ◽

Bulk Alloys

AbstractCd0.91Zn0.09Te/CdTe multilayers of various period thicknesses were inserted into Cd0.955Zn0.045Te bulk alloys grown on (001) GaAs. The net strain of the multilayer on the underlying Cd0.955Zn0.045Te was designed to be zero. X-ray diffraction full width at half maximum (FWHM) was used as a means to optimize the period thickness of the multilayer. Transmission electron microscopy of the optimum period thickness samples demonstrated four orders of magnitude decrease in the threading dislocation density. Mechanism of bending by equi-strained multilayers is discussed.

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

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100167196 ◽

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

MRS Proceedings ◽

10.1557/proc-743-l1.8 ◽

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.

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Threading Dislocations in InxGabxAs/GaAs System

MRS Proceedings ◽

10.1557/proc-240-123 ◽

1991 ◽

Vol 240 ◽

Author(s):

M. Tamura ◽

A. Hashimoto ◽

Y. Nakatsugawa

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Film Thickness ◽

Cross Section ◽

Molecular Beam ◽

Threading Dislocation ◽

Threading Dislocations ◽

Edge Type ◽

Transmission Electron ◽

Fixed Film

ABSTRACTThreading dislocation morphologies and characters, as well as their generation conditions in InxGa1−xAs films grown by molecular-beam epitaxy on GaAs (001) substrates have been examined, mainly using cross-section al transmission electron microscopy (XTEM) as a function of x and film thickness. The formation of severe threading dislocations is detected in epilayers ofx≧0.2 at a fixed film thickness of 3 μm and with film thicknesses greater than 2μmat x=0.2. Most of the observed threading dislocations are 60°- and pure-edge type dislocations along the <211> and [001] directions, respectively. The former type dislocations are mainly observed in layers of x≧0.2; the latter predominantly exist in layers of X≧O.3.

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Defect Reduction in Cd1−xZnxTe Epilayers on GaAs Substrates

MRS Proceedings ◽

10.1557/proc-302-439 ◽

1993 ◽

Vol 302 ◽

Author(s):

Saket Chadda ◽

Kevin Malloy ◽

John Reno

Keyword(s):

Threading Dislocation ◽

Full Width ◽

X Ray Diffraction ◽

Defect Reduction ◽

X Ray ◽

Gaas Substrates ◽

Transmission Electron ◽

Threading Dislocation Density ◽

Optimum Period ◽

Bulk Alloys

ABSTRACTCd0.91Zn0.09Te/CdTe multilayers of various period thicknesses were inserted into Cd0.955Zn0.045Te bulk alloys grown on (001) GaAs. The net strain of the multilayer on the underlying Cd0.955Zn0.045Te was designed to be zero. X-ray diffraction full width at half maximum (FWHM) was used as a means to optimize the period thickness of the multilayer. Transmission electron microscopy of the optimum period thickness samples demonstrated four orders of magnitude decrease in the threading dislocation density. Mechanism of bending by equi-strained multilayers is discussed.

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Microstructural study of GaAs epitaxial layers on Ge(100) substrates

Journal of Materials Research ◽

10.1557/jmr.1995.0843 ◽

1995 ◽

Vol 10 (4) ◽

pp. 843-852 ◽

Cited By ~ 8

Author(s):

N. Guelton ◽

R.G. Saint-Jacques ◽

G. Lalande ◽

J-P. Dodelet

Keyword(s):

Electron Microscopy ◽

Surface Preparation ◽

Growth Conditions ◽

Vapor Transport ◽

Threading Dislocations ◽

Misfit Dislocations ◽

Antiphase Boundaries ◽

Microstructural Study ◽

Mismatch Strain ◽

Transmission Electron

GaAs layers grown by close-spaced vapor transport on (100) Ge substrates have been investigated as a function of the experimental growth conditions. The effects on the microstructure of the surface preparation, substrate misorientation, and annealing were studied using optical microscopy and transmission electron microscopy. Microtwins and threading dislocations are suppressed by oxide desorption before deposition. Single domain GaAs layers have been obtained using a 50 nm thick double domain buffer layer on an annealed Ge substrate misoriented 3°toward [011]. The mismatch strain is mainly accommodated by dissociated 60°dislocations. These misfit dislocations extend along the interface by the glide of the threading dislocations inherited from the substrate, but strong interaction with antiphase boundaries (APB's) prevents them from reaching the interface. These results are discussed and compared with previous reports of GaAs growth on Ge(100).

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Defect-Engineered Graded GexSi1-x Buffers on Si (001) with Extreme Low Threading Dislocation Density

MRS Proceedings ◽

10.1557/proc-378-141 ◽

1995 ◽

Vol 378 ◽

Cited By ~ 2

Author(s):

G. Kissinger ◽

T. Morgenstern ◽

G. Morgenstern ◽

H. B. Erzgräber ◽

H. Richter

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Atomic Force Microscopy ◽

Dislocation Density ◽

Threading Dislocation ◽

Force Microscopy ◽

Atomic Force ◽

Transmission Electron ◽

Dislocation Densities ◽

Threading Dislocation Density

AbstractStepwise equilibrated graded GexSii-x (x≤0.2) buffers with threading dislocation densities between 102 and 103 cm−2 on the whole area of 4 inch silicon wafers were grown and studied by transmission electron microscopy, defect etching, atomic force microscopy and photoluminescence spectroscopy.

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Microstructral Investigations on GaN Films Grown by Laser Induced Molecular Beam Epitaxy

MRS Proceedings ◽

10.1557/proc-595-f99w3.58 ◽

1999 ◽

Vol 595 ◽

Cited By ~ 1

Author(s):

H. Zhou ◽

F. Phillipp ◽

M. Gross ◽

H. Schröder

Keyword(s):

Molecular Beam Epitaxy ◽

Molecular Beam ◽

Threading Dislocations ◽

Planar Defects ◽

Sapphire Substrates ◽

Inversion Domain ◽

Transmission Electron ◽

Domain Boundaries ◽

Line Defects ◽

Inversion Domain Boundaries

AbstractMicrostructural investigations on GaN films grown on SiC and sapphire substrates by laser induced molecular beam epitaxy have been performed. Threading dislocations with Burgers vectors of 1/3<1120>, 1/3<1123> and [0001] are typical line defects, predominantly the first type of dislocations. Their densities are typically 1.5×1010 cm−2 and 4×109 cm−2 on SiC and sapphire, respectively. Additionally, planar defects characterized as inversion domain boundaries lying on {1100} planes have been observed in GaN/sapphire samples with an inversion domain density of 4×109 cm−2. The inversion domains are of Ga-polarity with respect to the N-polarity of the adjacent matrix. However, GaN layers grown on SiC show Ga-polarity. Possible reasons for the different morphologies and structures of the films grown on different substrates are discussed. Based on an analysis of displacement fringes of inversion domains, an atomic model of the IDB-II with Ga-N bonds across the boundary was deduced. High resolution transmission electron microscopy (HRTEM) observations and the corresponding simulations confirmed the IDB-II structure determined by the analysis of displacement fringes.

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Transmission Electron Microscopy Studies of Strained Si CMOS

MRS Proceedings ◽

10.1557/proc-864-e4.31 ◽

2005 ◽

Vol 864 ◽

Author(s):

Qianghua Xie ◽

Peter Fejes ◽

Mike Kottke ◽

Xiangdong Wang ◽

Mike Canonico ◽

...

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Scanning Transmission Electron Microscopy ◽

Structural Information ◽

Threading Dislocation ◽

Misfit Dislocations ◽

Strained Si ◽

Thermal Budget ◽

Transmission Electron ◽

Scanning Transmission

AbstractIn this paper, various types of defects (both threading dislocation and misfit dislocations) in strained Si (sSi) have been analyzed by transmission electron microscopy (TEM). Germanium upper-diffusion has been studied by scanning transmission electron microscopy (STEM) for strained Si on SiGe/SOI. SGOI-devices processed using an optimized thermal budget show minimal Ge diffusion and minimal process related defects. Correlation between the device performance (such as leakage current and reliability) and structural information found in TEM has been established.

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Threading Dislocation Density Reduction in GaN/Sapphire Heterostructures.

MRS Proceedings ◽

10.1557/proc-595-f99w3.56 ◽

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.

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