Ordered Structures of Zn1−xFexSe Epilayers Grown on InP and GaAs Substrates

1993 ◽  
Vol 312 ◽  
Author(s):  
K. Park ◽  
H.- Y. Wei ◽  
L. Salamanca-Riba ◽  
B. T. Jonker
Keyword(s):  
Lattice Mismatch ◽  
Misfit Strain ◽  
Growth Direction ◽  
Ordered Structure ◽  
Cross Sectional ◽  
Ordered Structures ◽  
Gaas Substrates ◽  
Lattice Images ◽  
Diffraction Patterns ◽  
Inp Substrates

AbstractWe present evidence for two types of ordered structures, CuAu-I and CuPt, in Zn1−xFexSe (x≈ 0.4) epilayers grown by molecular beam epitaxy. These ordered structures are observed in both electron diffraction patterns and cross-sectional high-resolution lattice images. The CuAu-I ordered structure occurs in Zn1−xFexSe epilayers grown on (001) InP substrates, while the CuPt-type occurs in epilayers grown on (001) GaAs substrates. The ordered structure of Zn1−xFexSe grown on InP substrates consists of alternating ZnSe and FeSe layers along the [001] growth direction and the [110] direction. In contrast, the ordered structure of Zn1−xFexSe grown on GaAs substrates consists of alternating ZnSe and FeSe layers along the < 111 > directions. We have also investigated the role of the misfit strain associated with the lattice mismatch between the epilayers and the substrates on the type of ordered structure.

Ordering In Zn0.5Fe0.5Se Epilayers Grown on InP Substrates by Molecular Beam Epitaxy

1991 ◽  
Vol 231 ◽  
Author(s):  
L. Salamanca Riba ◽  
K. Park ◽  
B. T. Jonker
Keyword(s):  
High Resolution ◽  
Ordered Structure ◽  
Cross Sectional ◽  
Zinc Blende ◽  
Transmission Electron ◽  
Lattice Images ◽  
High Resolution Images ◽  
Diffraction Patterns ◽  
Inp Substrates ◽  
Image Simulations

AbstractWe have observed an ordered structure in Zn0.5Fe0.5Se epilayers grown on (001) InP substrates using transmission electron microscopy. The ordered structure of Zn0.5Fe0.5Se has Fe atoms occupying the (0,0,0) and (½, ½, 0) sites and Zn atoms occupying the (0, ½, ½) and (½, 0, ½) sites in the zinc-blende unit cell. Ordering is observed in both electron diffraction patterns and cross-sectional high-resolution lattice images along the < 100 > and < 110 > directions. This ordered structure consists of alternating ZnSe and FeSe monolayers along the < 100 > and < 110 > directions. Computer image simulations of the high-resolution images under various thicknesses, and defocusing conditions have been obtained and are compared with those obtained experimentally.

Defect Characterization of InAs Films Grown by Two-Step MOCVD on (100) InP Substrates

1992 ◽  
Vol 280 ◽  
Author(s):  
A. K. Ballal ◽  
L. Salamanca-Riba ◽  
D. L. Partin
Keyword(s):  
Electron Microscopy ◽  
Lattice Mismatch ◽  
Misfit Strain ◽  
Organic Chemical ◽  
Threading Dislocations ◽  
Misfit Dislocations ◽  
Epitaxial Relationship ◽  
Cross Sectional ◽  
Plan View ◽  
Inp Substrates

ABSTRACTIn this paper we investigate the defect morphology and misfit strain in InAs films grown on (100) InP substrates using two-step metal organic chemical vapor deposition (MOCVD). High quality InAs films were obtained despite the 3.2% lattice-mismatch between the InAs film and the InP substrate. Cross-sectional and plan-view transmission electron microscopy has been used to characterize the ∼3μm thick InAs films. Almost all the lattice mismatch is accomodated by an orthogonal array of pure edge Lomer dislocations which are favored over the 60° type since they are more efficient in relieving misfit strain. In addition to misfit dislocations, threading dislocations were observed propagating through the film. Most of the threading dislocations were 60° type dislocations along the < 211 > and < 110 > directions on inclined {111} planes. The threading dislocations originate from island coalescence during film growth. High resolution electron microscopy shows the epitaxial relationship between the film and the substrate and reveals an abrupt and sharp interface with periodic dislocation cores.

Planar defects in ordered (Ga,In)P

1988 ◽  
Vol 46 ◽  
pp. 902-903
Author(s):  
S. McKernan ◽  
C. B. Carter ◽  
D. Bour ◽  
J. R. Shealy
Keyword(s):  
Electron Diffraction ◽  
Vapor Phase ◽  
Growth Direction ◽  
High Density ◽  
Ordered Structure ◽  
Planar Defects ◽  
Diffraction Patterns ◽  
Ternary Semiconductors ◽  
Anion Species ◽  
Metallic Vapor

The growth of ternary III-V semiconductors by organo-metallic vapor phase epitaxy (OMVPE) is widely practiced. It has been generally assumed that the resulting structure is the same as that of the corresponding binary semiconductors, but with the two different cation or anion species randomly distributed on their appropriate sublattice sites. Recently several different ternary semiconductors including AlxGa1-xAs, Gaxln-1-xAs and Gaxln1-xP1-6 have been observed in ordered states. A common feature of these ordered compounds is that they contain a relatively high density of defects. This is evident in electron diffraction patterns from these materials where streaks, which are typically parallel to the growth direction, are associated with the extra reflections arising from the ordering. However, where the (Ga,ln)P epilayer is reasonably well ordered the streaking is extremely faint, and the intensity of the ordered spot at 1/2(111) is much greater than that at 1/2(111). In these cases it is possible to image relatively clearly many of the defects found in the ordered structure.

TEM Evaluation of CuAu-I Type Ordered Structures in MBE grown Ingaas Crystals on (110) Inp Substrates

1990 ◽  
Vol 209 ◽  
Author(s):  
O. Ueda ◽  
Y. Nakata ◽  
T. Nakamura ◽  
T. Fujii
Keyword(s):  
Electron Microscopy ◽  
Molecular Beam ◽  
Growth Surface ◽  
Ordered Structure ◽  
Phase Boundaries ◽  
Ordered Structures ◽  
Transmission Electron ◽  
Tilting Angle ◽  
High Resolution Images ◽  
Inp Substrates

ABSTRACTCuAu-I type ordered structures in InGaAs grown on (110) InP substrates by molecular beam epitaxy, have been studied by transmission electron microscopy. In the electron diffraction pattern from the InGaAs, superstructure spots associated withCuAu-I type ordered structure are found. When the tilting angle of the substrates increases, the ordering becomes stronger. The ordering is also stronger in crystals grown on substrates tilted toward the <001> or the <001> direction than those on substrates tilted toward the <110> direction. From these results, one can conclude that atomic steps on the growth surface play an important role in the formation of ordered structures. The ordering becomes stronger when the growth temperature increases in the range 360-485°C. In high resolution images of the crystal, doubling in periodicity of 220 and 200lattice fringes is found, which is associated with CuAu-I type ordered structure. Moreover, anti-phase boundaries are very often observed in the ordered regions. It is also found that ordering is not perfect, and that ordered regions are plate-like microdomains lying on planes slightly tilted from the (110) plane.

Interpretation of electron diffraction patterns in the presence of oriented planar faults

2015 ◽  
Vol 48 (6) ◽  
pp. 1921-1926 ◽  
Author(s):  
S. J. B. Kurz ◽  
A. Leineweber ◽  
E. J. Mittemeijer
Keyword(s):  
Thin Films ◽  
Perfect Match ◽  
Growth Direction ◽  
Fiber Texture ◽  
Fiber Axis ◽  
Face Centered Cubic ◽  
Cross Sectional ◽  
Diffuse Intensity ◽  
Axis Parallel ◽  
Diffraction Patterns

The presence of high planar-fault densities in thin films,e.g.nanotwinned films, leads to peculiar diffraction effects. Frequently, the planar faults are oriented perpendicular to the growth direction. For the case of (nanosized) thin films of face-centered cubic (fcc) metals, often a {111}fccfiber texture prevails with the fiber axis parallel to the film normal. In diffraction patterns of cross-sectional transmission electron microscopy (TEM) samples of such films, as a consequence of twinning with (111) planes parallel to the surface as twinning planes, intensity streaks appear parallel to the growth direction. These intensity streaks are, however, invisible in diffraction patterns of top-view TEM samples. The latter diffraction patterns might be interpreted, at first sight, in terms of the diffraction pattern of a somehow textured fcc polycrystal. However, the diffraction-ring radii deviate from the expected radii. The consideration of intensity cylinders in reciprocal space formed by diffuse intensity streaks generated by the planar faults leads to a perfect match of the accordingly predicted radii with the observed intensity-ring radii.

Ordered Structures of Zn1-xFexSe Epilayers Grown on GaAs Substrates with ZnSe Buffer Layers

1994 ◽  
Vol 340 ◽  
Author(s):  
H.-Y. Wei ◽  
D. Prasad Beesabathina ◽  
L. Salamanca-Riba ◽  
B. T. Jonker
Keyword(s):  
Buffer Layer ◽  
Hexagonal Structure ◽  
Buffer Layers ◽  
Ordered Structure ◽  
Rough Interface ◽  
Triangular Form ◽  
Ordered Structures ◽  
X Ray ◽  
Gaas Substrates ◽  
Transmission Electron

ABSTRACTWe observed the coexistence of two types of ordered structures, Cu3Au and CuPt, in Zn0.4Fe0.6Se epilayers grown on ZnSe buffer layers on (001) GaAs substrates by transmission electron microscopy. In addition, the Cu3Au ordered structure exists with a multi-faceted domain shape. Energy dispersive x-ray spectra from these domains showed higher Fe concentration than in the disordered matrix. However, in Zn0.5Fe0.5Se epilayers, we only observed CuAu-I ordered multi-faceted domains. The samples with relatively high Fe concentration (x ≈0.6) also showed domains of FeSe with a hexagonal structure with triangular form coexisting with Cu3Au ordered domains. Strain-induced interdiffusion takes place between the buffer layer and the epilayer as evidenced by a rough interface between the alloy and the buffer layer.

Structure and Morphology of MBE Fabricated Zn0.5Fe0.5Se On GaAs as a Function of Substrate Preparation and Growth Temperature

1996 ◽  
Vol 441 ◽  
Author(s):  
H.-Y. Wei ◽  
L. Salamanca-Riba ◽  
J. Smathers ◽  
B. T. Jonker
Keyword(s):  
Growth Temperature ◽  
Film Growth ◽  
Diluted Magnetic Semiconductor ◽  
Magnetic Semiconductor ◽  
Ordered Structure ◽  
Substrate Preparation ◽  
Cross Sectional ◽  
Different Temperatures ◽  
Lattice Images ◽  
Diluted Magnetic

AbstractWe have recently reported the observation of CuAu-I, CuPt, and Cu3Au ordered structures in the diluted magnetic semiconductor Zn1−xFexSe grown by molecular beam epitaxy for different values of the Fe concentration. In the present work, we grew a series of samples with identical Fe composition (x=0.5) but for a range of growth temperatures (from 250 °C to 450 °C). By using transmission electron microscopy, ordering along the <001> and <110> directions was observed in both electron diffraction patterns and cross-sectional high-resolution lattice images corresponding to the CuAu-I ordered structure of Zn0.5Fe0.5Se. However, this ordered structure coexists with a tetragonal FeSe structure and forms large, well defined faceted domains. At the higher growth temperature, the number of faceted domains increases as observed by atomic force microscopy. Pure FeSe films were also grown at different temperatures for comparison. The influence of substrate preparation before film growth is also discussed.

Characterization of Interfacial Structure in Large Lattice Mismatch Heteroepitaxy: Ag/Si (111)

1990 ◽  
Vol 209 ◽  
Author(s):  
D.C. McKenna ◽  
G.-C. Wang ◽  
K. Rajan
Keyword(s):  
Lattice Mismatch ◽  
Interfacial Structure ◽  
Epitaxial Relationship ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Interfacial Structures ◽  
Large Lattice ◽  
Large Lattice Mismatch ◽  
Diffraction Patterns

ABSTRACTThe interfacial structure of a large lattice mismatched (˜25%) (111) Ag-Si system was studied by using transmission electron diffraction (SADP - Selected Area Diffraction Pattern). The epitaxial films of Ag (600–1200Å) were grown by MBE on flat Si(111) and misoriented Si(1ll) surfaces. We have examined the interfacial structures of the Ag on 2° misoriented Si(111) using diffraction patterns of cross sectional view. Through a detail analysis of thelocation and shape of the diffraction spots, we can determine the epitaxial relationship between Ag and Si, the small tilt angle of Ag(111) planes withrespect to the misoriented Si(111), the period of the finite terrace size of the misoriented Si substrate, and the size of the ordered region in the Ag film. The O-lattice analysis developed by Bollmann has beenapplied to this interface andthe result is compared with the SADP observation.

scholarly journals Metamorphic Integration of GaInAsSb Material on GaAs Substrates for Light Emitting Device Applications

Materials ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 1743
Author(s):  
Qi Lu ◽  
Andrew Marshall ◽  
Anthony Krier
Keyword(s):  
Quantum Wells ◽  
Buffer Layer ◽  
Lattice Mismatch ◽  
Cost Effective ◽  
Threading Dislocations ◽  
Cross Sectional ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Gaas Substrates ◽  
Device Applications

The GaInAsSb material has been conventionally grown on lattice-matched GaSb substrates. In this work, we transplanted this material onto the GaAs substrates in molecular beam epitaxy (MBE). The threading dislocations (TDs) originating from the large lattice mismatch were efficiently suppressed by a novel metamorphic buffer layer design, which included the interfacial misfit (IMF) arrays at the GaSb/GaAs interface and strained GaInSb/GaSb multi-quantum wells (MQWs) acting as dislocation filtering layers (DFLs). Cross-sectional transmission electron microscopy (TEM) images revealed that a large part of the dislocations was bonded on the GaAs/GaSb interface due to the IMF arrays, and the four repetitions of the DFL regions can block most of the remaining threading dislocations. Etch pit density (EPD) measurements indicated that the dislocation density in the GaInAsSb material on top of the buffer layer was reduced to the order of 106 /cm2, which was among the lowest for this compound material grown on GaAs. The light emitting diodes (LEDs) based on the GaInAsSb P-N structures on GaAs exhibited strong electro-luminescence (EL) in the 2.0–2.5 µm range. The successful metamorphic growth of GaInAsSb on GaAs with low dislocation densities paved the way for the integration of various GaInAsSb based light emitting devices on the more cost-effective GaAs platform.

Atomic Ordering of III-V Alloy Semiconductors Grown on (110)InP and its Influence on Electron Mobility

1995 ◽  
Vol 417 ◽  
Author(s):  
O. Ueda
Keyword(s):  
Electron Diffraction ◽  
Growth Surface ◽  
Ordered Structure ◽  
Atomic Ordering ◽  
Ordered Structures ◽  
Limited Mobility ◽  
Alloy Scattering ◽  
Channel Layer ◽  
Diffraction Patterns ◽  
Dimensional Electron Gas

AbstractAtomic ordering in InGaAs, InAlAs, and GaAsSb crystals grown on (110) InP substrates by molecular beam epitaxy, has been studied by transmission electron microscopy. In the electron diffraction pattern from these crystals, superstructure spots associated with CuAu-I type ordered structure are found. When the tilting angle of the substrates increases, the ordering becomes stronger. The ordering is also stronger in crystals grown on substrates tilted toward the <001> or the <001> direction than those on substrates tilted toward the <110> direction. From these results, one can conclude that atomic steps on the growth surface play an important role in the formation of ordered structures. The ordering becomes stronger when the growth temperature increases. In high resolution images of the crystal, doubling in periodicity of 220 and 200 lattice fringes is found, which is associated with CuAu-I type ordered structure. Moreover, anti-phase boundaries are very often observed in the ordered regions. It is also found that ordering is not perfect, and that ordered regions are plate-like microdomains lying on planes slightly tilted from the (110) plane. On the basis of these results together with considerations of the atomic arrangement of the ordered structure and surface reconstruction on the (110) plane, we propose four possible models for the ordering. Through precise evaluation of these models, two models are selected as the most probable ones: these involve formation of the ordered structures on surfaces dominated by two monolayer steps. These models have been experimentally proven by the analyses of electron diffraction patterns from different InGaAs crystals grown on different growth surfaces. We have fabricated InGaAs/N-InAlAs heterostructures with a strongly ordered InGaAs channel layer. The measured two-dimensional electron gas mobilities from these structures are found to be 100,000 cm2/Vs in the <110> direction and 161,000 cm2/Vs in the <110> direction with a sheet electron concentration (Ns) of 9.5 × 1011 cm−2 at 6 K. The latter mobility is much higher than both calculated alloy scattering limited mobility and the best experimental results for lattice-matched InGaAs/N-InA]As systems. The mobility enhancement in the <110> direction is considered to be achieved by the suppression of alloy scattering due to the occurrence of ordering in the InGaAs channel layer.

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