A Systematic TEM and Rheed Investigation of the MBE Growth of InxGa1−xAs a Function of Composition

1990 ◽  
Vol 216 ◽  
Author(s):  
S.P. Edirisinghe ◽  
A.E. Staton-Bevan ◽  
D.W. Pashley ◽  
P. Fawcett ◽  
B.A. Joyce
Keyword(s):  
Buffer Layer ◽  
Misfit Strain ◽  
Growth Mode ◽  
Threading Dislocations ◽  
Misfit Dislocations ◽  
Mbe Growth

ABSTRACT0.15µm epilayers of InxGa1−xAs grown on GaAs (001) by MBE, having In concentrations in the range x = 0.05 - 0.30, have been investigated using RHEED and TEM. RHEED patterns indicate a 2-D growth mode for low In concentrations changing to Stranski-Krastanov growth for x > 0.30. TEM showed misfit dislocations for x > 0.05 only, which were found to relieve only a small part of the misfit strain. Although threading dislocations were rarely found in the epilayers, dislocations originating at the interface and penetrating the buffer layer were observed for 0.1 < x < 0.25.

The Initial Stages of MBE Growth of InSb on GaAs(100) - A High Misfit Heterointerface

1989 ◽  
Vol 159 ◽  
Author(s):  
C.J. Kiely ◽  
A. Rockett ◽  
J-I. Chyi ◽  
H. Morkoc
Keyword(s):  
Three Dimensional ◽  
Misfit Strain ◽  
Threading Dislocations ◽  
Misfit Dislocations ◽  
Island Growth ◽  
Mbe Growth ◽  
Edge Type ◽  
Transmission Electron ◽  
Interfacial Defects ◽  
Square Array

ABSTRACTThe initial stages of heteroepitaxy of InSb on GaAs(100) grown by MBE have been studied by transmission electron microscopy. Three dimensional InSb island growth occurs in which the majority of the 14.6% misfit strain is accommodated by a square array of a/2<011= edge-type misfit dislocations. The implications of each island having a well defined defect array before coalescence into a continuous epilayer are discussed. Some 600-type a/2<101= interfacial defects and associated threading dislocations are also observed in coalesced films and possible reasons for their existence are explained. A strong asymmetrical distribution of planar defects in the InSb islands is observed and the origin of the asymmetry is discussed. Finally some evidence for local intermixing in the vicinity of the interface is presented.

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.

Tem Investigation of Strain Relaxation in ZnSe/ZnSxSe1−x Superlattices Grown by MBE

1987 ◽  
Vol 104 ◽  
Author(s):  
J. Petruzzello ◽  
O. Boser ◽  
P. Kellawon
Keyword(s):  
Molecular Beam Epitaxy ◽  
Buffer Layer ◽  
Molecular Beam ◽  
Strain Relaxation ◽  
Misfit Strain ◽  
Misfit Dislocations ◽  
Individual Layer ◽  
Layer Interface

ABSTRACTThe relaxation mechanisms of ZnSe/ZnSxSe1−x superlattices grown by molecular beam epitaxy was studied by transmission rAeclmn icroscopy. The relaxation of misfit strain occured in part by conventional misfit dislocations that reside in the superlattice-buffer layer interface and in part by dislocations pinned at individual layer interfaces of the superlattice. The generation of misfit dislocations at the superlattice-buffer layer interface is inhibited by the misfit strain between individual superlattice layers. Therefore a significant amount of overall strain is present even after 1 μm of growth. Because misfit dislocations are not sufficient in relief of the misfit strain cracks are able to propagate

Evolution of Stress and Relaxation of Strain of Ge and SiGe Alloy Films on Si(001)

2001 ◽  
Vol 696 ◽  
Author(s):  
R. Koch ◽  
J. J. Schulz ◽  
B. Wassermann ◽  
G. Wedler
Keyword(s):  
Strain Relaxation ◽  
Misfit Strain ◽  
Growth Mode ◽  
Ex Situ ◽  
Scanning Tunneling ◽  
Misfit Dislocations ◽  
Tunneling Microscopy ◽  
Structural Investigations ◽  
Alloy Films ◽  
Sige Alloy

AbstractWe report on real time stress measurements by a sensitive cantilever beam technique of Ge and SiGe Alloy Films on Si(001) in combination with structural investigations by in situ STM (scanning tunneling microscopy) and ex situ AFM (atomic force microscopy). Characteristic features in the stress curves provide detailed insight into the development and relief of the misfit strain as well as the respective growth mode. For the Stranski-Krastanow system Ge/Si(001) the strain relaxation proceeds mainly in two steps: (i) by the formation of 3D islands on top of the Ge wetting layer and (ii) via misfit dislocations in larger 3D islands and upon their percolation. Co-deposition of Si influences the stress behavior drastically. The growth mode changes from Stranski-Krastanow to a kinetic 3D island mode at Si concentrations of about 20% leading to the so far smallest quantum dots of the Ge/Si system.

Effects of misfit dislocations and AlN buffer layer on the GaInN/GaN phase diagram of the growth mode

2001 ◽  
Vol 89 (1) ◽  
pp. 146-153 ◽  
Author(s):  
Kazuo Nakajima ◽  
Toru Ujihara ◽  
Satoru Miyashita ◽  
Gen Sazaki
Keyword(s):  
Phase Diagram ◽  
Buffer Layer ◽  
Growth Mode ◽  
Misfit Dislocations ◽  
Aln Buffer

Anisotropy of interfacial defects in the initial stage of MOVPE GaAs growth On Si

1990 ◽  
Vol 48 (4) ◽  
pp. 592-593
Author(s):  
C. Vannuffel ◽  
C. Schiller ◽  
J. P. Chevalier
Keyword(s):  
Early Stage ◽  
Threading Dislocations ◽  
Mbe Growth ◽  
Detailed Mechanism ◽  
Si Substrates ◽  
Initial Stage ◽  
Interfacial Defects ◽  
Interfacial Dislocations ◽  
Step Growth ◽  
Essential Problem

Recently, interest has focused on the epitaxy of GaAs on Si as a promising material for electronic applications, potentially for integration of optoelectronic devices on silicon wafers. The essential problem concerns the 4% misfit between the two materials, and this must be accommodated by a network of interfacial dislocations with the lowest number of threading dislocations. It is thus important to understand the detailed mechanism of the formation of this network, in order to eventually reduce the dislocation density at the top of the layers.MOVPE growth is carried out on slightly misoriented, (3.5°) from (001) towards , Si substrates. Here we report on the effect of this misorientation on the interfacial defects, at a very early stage of growth. Only the first stage, of the well-known two step growth process, is thus considered. Previously, we showed that full substrate coverage occured for GaAs thicknesses of 5 nm in contrast to MBE growth, where substantially greater thicknesses are required.

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

1995 ◽  
Vol 10 (4) ◽  
pp. 843-852 ◽  
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).

Dislocation Nucleation and Growth in MOCVD GaN/AlN Films on Stepped and Step-free 4H-SiC Mesa Substrates

2008 ◽  
Vol 1090 ◽  
Author(s):  
Mark E. Twigg ◽  
Yoosuf N. Picard ◽  
Nabil D. Bassim ◽  
Joshua D. Caldwell ◽  
Michael A. Mastro ◽  
...  
Keyword(s):  
Dominant Role ◽  
High Stress ◽  
Chemical Vapor ◽  
Misfit Strain ◽  
Nucleation And Growth ◽  
Dislocation Nucleation ◽  
Threading Dislocations ◽  
Surface Steps ◽  
Half Loop ◽  
Edge Dislocations

AbstractUsing transmission electron microscopy, we have analyzed dislocations in AlN nucleation layers and GaN films grown by metallorganic chemical vapor deposition (MOCVD) on the (0001) surface of epitaxially-grown 4H-SiC mesas with and without steps. For 4H-SiC substrates free of SiC surface steps, half-loop nucleation and glide parallel to the AlN/SiC interfacial plane play the dominant role in strain relief, with no mechanism for generating threading dislocations. In contrast, 4H-SiC mesa surfaces with steps give rise to regions of high stress at the heteroepitaxial interface, thereby providing an environment conducive to the nucleation and growth of threading dislocations, which act to accommodate misfit strain by the tilting of threading edge dislocations.

Observation of GaAs/Si Epitaxial Interfaces by Atomic Resolution Electron Microscopy

1986 ◽  
Vol 67 ◽  
Author(s):  
N. Otsuka ◽  
C. Choi ◽  
Y. Nakamura ◽  
S. Nagakura ◽  
R. Fischer ◽  
...  
Keyword(s):  
Substrate Surface ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Threading Dislocations ◽  
Misfit Dislocations ◽  
Si Substrates ◽  
Voltage Electron ◽  
Resolution Electron ◽  
Gaas Films ◽  
Substrate Surfaces

ABSTRACTRecent studies have shown that high quality GaAs films can be grown by MBE on Si substrates whose surfaces are slightly tilted from the (100) plane. In order to investigate the effect of the tilting of substrate surfaces on the formation of threading dislocations, the GaAs/Si epitaxial interfaces have been observed with a 1 MB ultra-high vacuum, high voltage electron microscope. Two types of misfit dislocations, one with Burgers vectors parallel to the interface and the other with Burgers vectors inclined from the interface, were found in these epitaxial interfaces. The observation of crosssectional samples perpendicular to each other has shown that the tilting of the substrate surface directly influences the generation of these two types of misfit dislocations. The mechanism of the reduction of threading dislocations by the tilting of the substrate surface is discussed based on these observations.

Epitaxial Lateral Overgrowth of GaN on SiC and Sapphire Substrates

1998 ◽  
Vol 537 ◽  
Author(s):  
Zhonghai Yu ◽  
M.A.L. Johnson ◽  
J.D. Brown ◽  
N.A. El-Masry ◽  
J. F. Muth ◽  
...  
Keyword(s):  
Single Crystal ◽  
Epitaxial Lateral Overgrowth ◽  
Threading Dislocations ◽  
Growth Processes ◽  
Mbe Growth ◽  
Sapphire Substrates ◽  
Lateral Overgrowth ◽  
Movpe Growth ◽  
Gan Film ◽  
Growth Experiments

AbstractThe epitaxial lateral overgrowth (ELO) process for GaN has been studied using SiC and sapphire substrates. Both MBE and MOVPE growth processes were employed in the study. The use of SiO2 versus SiNx insulator stripes was investigated using window/stripe widths ranging from 2 μm/4 μm to 3 μm/15 μm. GaN film depositions were completed at temperatures ranging from 800°C to 1120°C. Characterization experiments included RHEED, TEM, SEM and cathodolumenescence studies. The MBE growth experiments produced polycrystalline GaN over the insulator stripes even at deposition temperatures as high as 990°C. In contrast, MOVPE growth produced single-crystal GaN stripes with no observable threading dislocations.

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