Electron microscopy of GaAs grown on Si- and Ge-based substrates

1991 ◽  
Vol 49 ◽  
pp. 854-855
Author(s):  
D.P. Malta ◽  
J.B. Posthill ◽  
M.L. Timmons ◽  
P.R. Sharps ◽  
R. Venkatasubramanian ◽  
...  
Keyword(s):  
Critical Thickness ◽  
Lattice Mismatch ◽  
Low Cost ◽  
Antiphase Domain ◽  
Threading Dislocation ◽  
Misfit Dislocations ◽  
Thermally Induced ◽  
Induced Stress ◽  
Dislocation Reduction ◽  
Domain Boundaries

A GaAs-on-Si technology is desirable to take advantage of the mobility and direct bandgap of GaAs in combination with the crystalline quality, low cost and established technology of Si. Differences in lattice constant (4.1%), thermal expansion coefficient (a factor of ~ 3), and bonding polarity between the two materials can lead to problems such as: threading dislocation formation, thermally induced stress and delamination, and antiphase domain boundaries (APBs), respectively. The lattice mismatch is responsible for the formation of (necessary) misfit dislocations which can concurrently create threading dislocations with typical densities in the range of 106 - 108cm-2. This density of electrically active defects in a device region is highly undesirable.A proposed scheme for lattice mismatch accommodation and potential threading dislocation reduction has previously been reported in which each layer of a SixGe1-x multilayer structure (MLS) is grown beyond the critical thickness with a progressively higher Ge composition than the previous layer.

Structural properties of GaAs/InGaAs/GaAs (001) and InGaAs/GaAs (001) heterostructures and correlation with electronic properties

1990 ◽  
Vol 48 (4) ◽  
pp. 602-603
Author(s):  
J.M. Bonar ◽  
R. Hull ◽  
R. Malik ◽  
R. Ryan ◽  
J.F. Walker
Keyword(s):  
Band Gap ◽  
Electronic Properties ◽  
Gaas Substrate ◽  
Critical Thickness ◽  
Lattice Mismatch ◽  
Band Offset ◽  
Misfit Dislocations ◽  
Gaas Substrates ◽  
Gaas Structure ◽  
Low X

In this study we have examined a series of strained heteropeitaxial GaAs/InGaAs/GaAs and InGaAs/GaAs structures, both on (001) GaAs substrates. These heterostructures are potentially very interesting from a device standpoint because of improved band gap properties (InAs has a much smaller band gap than GaAs so there is a large band offset at the InGaAs/GaAs interface), and because of the much higher mobility of InAs. However, there is a 7.2% lattice mismatch between InAs and GaAs, so an InxGa1-xAs layer in a GaAs structure with even relatively low x will have a large amount of strain, and misfit dislocations are expected to form above some critical thickness. We attempt here to correlate the effect of misfit dislocations on the electronic properties of this material.The samples we examined consisted of 200Å InxGa1-xAs layered in a hetero-junction bipolar transistor (HBT) structure (InxGa1-xAs on top of a (001) GaAs buffer, followed by more GaAs, then a layer of AlGaAs and a GaAs cap), and a series consisting of a 200Å layer of InxGa1-xAs on a (001) GaAs substrate.

MBE Growth and Characterization of SxGe1−x Multilayer Structures on Si (100) for Use as a Substrate for GaAs Heteroepitaxy

1991 ◽  
Vol 220 ◽  
Author(s):  
J. B. Posthill ◽  
D. P. Malta ◽  
R. Venkatasubramanian ◽  
P. R. Sharps ◽  
M. L. Timmons ◽  
...  
Keyword(s):  
Molecular Beam ◽  
Lattice Mismatch ◽  
Antiphase Domain ◽  
Multilayer Structures ◽  
Si Substrate ◽  
Mbe Growth ◽  
Etch Pit ◽  
Layer Structures ◽  
Domain Boundaries

ABSTRACTInvestigation has continued into the use of SixGe1−x multilayer structures (MLS) as a buffer layer between a Si substrate and a GaAs epitaxial layer in order to accommodate the 4.1% lattice mismatch. SixGe1−x 4-layer and 5-layer structures terminating in pure Ge have been grown using molecular beam epitaxy. Subsequent GaAs heteroepitaxy has allowed evaluation of these various GaAs/SixGe1−xMLS/Si (100) structures. Antiphase domain boundaries have been eliminated using vicinal Si (100) substrates tilted 6° off-axis toward [011], and the etch pit density in GaAs grown on a 5-layer SixGe1−x MLS on vicinal Si (lOO) was measured to be 106 cm−2.

Misfit dislocations and antiphase domain boundaries in GaAs/Si interface

1994 ◽  
Vol 75 (1) ◽  
pp. 143-152 ◽  
Author(s):  
Ph. Komninou ◽  
J. Stoemenos ◽  
G. P. Dimitrakopulos ◽  
Th. Karakostas
Keyword(s):  
Antiphase Domain ◽  
Misfit Dislocations ◽  
Domain Boundaries

Equilibrium Analysis of Lattice-Mismatched Nanowire Heterostructures

2002 ◽  
Vol 737 ◽  
Author(s):  
E. Ertekin ◽  
P.A. Greaney ◽  
T. D. Sands ◽  
D. C. Chrzan
Keyword(s):  
Simple Model ◽  
Misfit Dislocation ◽  
Critical Thickness ◽  
Lattice Mismatch ◽  
Equilibrium Analysis ◽  
Misfit Dislocations ◽  
Model Based ◽  
Large Lattice ◽  
Large Lattice Mismatch

ABSTRACTThe quality of lattice-mismatched semiconductor heterojunctions is often limited by the presence of misfit dislocations. Nanowire geometries offer the promise of creating highly mismatched, yet dislocation free heterojunctions. A simple model, based upon the critical thickness model of Matthews and Blakeslee for misfit dislocation formation in planar heterostructures, illustrates that there exists a critical nanowire radius for which a coherent heterostructured nanowire system is unstable with respect to the formation of misfit dislocations. The model indicates that within the nanowire geometry, it should be possible to create perfect heterojunctions with large lattice-mismatch.

CRITICAL THICKNESS FOR Nb NANOFILM ON SAPPHIRE SUBSTRATE: AN EXAMPLE TOWARD UNDERSTANDING EVOLUTION OF COHERENT NANOSTRUCTURES

2011 ◽  
Vol 10 (01n02) ◽  
pp. 351-354 ◽  
Author(s):  
ARUN KUMAR ◽  
ANANDH SUBRAMANIAM
Keyword(s):  
Stress State ◽  
Edge Dislocation ◽  
Sapphire Substrate ◽  
Critical Thickness ◽  
Lattice Mismatch ◽  
Energy Criterion ◽  
Misfit Dislocations ◽  
Combined Simulation ◽  
Triangular Network ◽  
Theoretical Analyses

On growth beyond critical thickness, interfacial misfit dislocations partially relax the misfit strains in epitaxially grown nanofilms. In this study the stress state and growth of nanofilms are simulated using Finite Element Method (FEM) by imposing stress-free strains, corresponding to the lattice mismatch between Nb nanofilm and Sapphire substrate. On growth of the Nb nanofilm, a triangular network of edge misfit dislocations nucleates at the (0001) Al 2 O 3∥(111) Nb interface. Using a combined simulation of a coherently strained nanofilm and an edge dislocation, the critical thickness for the nucleation of an edge dislocation is determined using an equilibrium energy criterion. Theoretical analyses in literature use only the component of the Burgers vector parallel to the interface, which is an erroneous description of the stress state and energetics of the system. In this investigation the full interfacial edge dislocation is simulated using standard commercially available software and comparisons are made with results available in literature to bring out the utility of the methodology.

Misfit dislocations between boron-doped homoepitaxial films and diamond substrates studied by X-ray diffraction topography

2018 ◽  
Vol 51 (6) ◽  
pp. 1684-1690 ◽  
Author(s):  
Marina González-Mañas ◽  
Beatriz Vallejo
Keyword(s):  
Critical Thickness ◽  
Lattice Mismatch ◽  
Lattice Parameter ◽  
Threading Dislocations ◽  
Misfit Dislocations ◽  
Boron Doped Diamond ◽  
X Ray ◽  
Boron Doped ◽  
Slip Planes ◽  
Half Loop

Boron-doped diamond epilayers grown over diamond substrates have a different lattice parameter from the undoped diamond substrate, which introduces a lattice mismatch between substrates and epilayers. This can generate misfit dislocations at the interface when the epilayer reaches a certain critical thickness. For a boron concentration of about 1 × 1020 atoms cm−3, the calculated lattice mismatch is about 1.3 × 10−4 and the critical thickness is of the order of 0.2 µm. In the epilayers studied, grown over high-pressure high-temperature 1b (001) substrates, the lattice mismatch and the epilayer thickness are 1.3 × 10−4, 30 µm and 6.5 × 10−4, 4 µm. The epitaxial strain has been relaxed by the generation of two orthogonal misfit dislocation systems. These are edge dislocations parallel to the [100] and [010] directions with a Burgers vector making an angle of 45° with the (001) interface. Their lengths are 40–60 µm and their lineal densities 200–240 cm−1. They are heterogeneously nucleated, propagated in the form of half-loops along the slip planes (011) and (101), respectively, and related mainly to 〈111〉 threading dislocations emerging from octahedral growth sectors. Another kind of half-loop originates from the substrate growth sector boundaries. Limited X-ray topography has been demonstrated to be a very useful tool to discriminate between substrate and epilayer defects when their lattice mismatch is not sufficient to separate such defects in conventional Lang topography. X-ray section topography has confirmed the presence of [001] dislocations in the epilayers and the misfit half-loops related to threading dislocations propagating from the interface.

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.

A Kinetic Model for the Strain Relaxation in Heteroepitaxial Thin Film Systems

2001 ◽  
Vol 673 ◽  
Author(s):  
Y.W. Zhang ◽  
T.C. Wang ◽  
S.J. Chua
Keyword(s):  
Thin Film ◽  
Surface Roughness ◽  
Kinetic Model ◽  
Strain Relaxation ◽  
Experimental Results ◽  
Threading Dislocation ◽  
Threading Dislocations ◽  
Misfit Dislocations ◽  
Dislocation Reduction ◽  
Wide Range

ABSTRACTA kinetic model is presented to simulate the strain relaxation in the GexSi1−x/Si(100) systems. In the model, the nucleation, propagation and annihilation of threading dislocations, the interaction between threading dislocations and misfit dislocations, and surface roughness are taken into account. The model reproduces a wide range of experimental results. The implications of its predictions on the threading dislocation reduction during the growth processes of the heteoepitaxial thin film systems are discussed.

Interface Effects in Strained Thin Films

2009 ◽  
Author(s):  
Andrew Robison ◽  
Lei Lei ◽  
Sowmya Ramarapu ◽  
Marisol Koslowski
Keyword(s):  
Thin Film ◽  
Lattice Mismatch ◽  
Semiconductor Industry ◽  
Threading Dislocation ◽  
Misfit Dislocations ◽  
Crystalline Films ◽  
Multiple Obstacles ◽  
Very High ◽  
Interface Effects

Crystalline films grown epitaxially on a substrate consisting of a different crystalline material are of considerable interest in optoelectronic devices and the semiconductor industry. The film and substrate have in general different lattice parameters. This lattice mismatch affects the quality of interfaces and can lead to very high densities of misfit dislocations. Here we study the evolution of these misfit dislocations in a single crystal thin film. In particular, we consider the motion of a dislocation gliding on its slip plane within the film and its interaction with multiple obstacles and sources. Our results show the effect of obstacles such as precipitates and other dislocations on the evolution of a threading dislocation in a metallic thin film. We also show that the material becomes harder as the film thickness decreases in excellent agreement with experiments.

Strain Relaxation and Dislocation Confinement in Epitaxial SrTiO3 by Two-Step Growth Technique and the Resulting Dielectric Response

2005 ◽  
Vol 902 ◽  
Author(s):  
Tomoaki Yamada ◽  
Vladimir O. Sherman ◽  
Alexander K. Tagantsev ◽  
Dong Su ◽  
Paul Muralt ◽  
...  
Keyword(s):  
Lattice Mismatch ◽  
Strain Relaxation ◽  
Effective Strain ◽  
Microwave Dielectric Properties ◽  
Threading Dislocation ◽  
Misfit Dislocations ◽  
Initial Growth ◽  
Growth Step ◽  
Growth Technique ◽  
Step Growth

AbstractA two-step growth technique was used to achieve effective strain relaxation and dislocation confinement of epitaxial SrTiO3(STO) films and through this to improve their microwave dielectric properties. The crystallization of a very thin quasi-amorphous STO layer deposited at a low temperature in the initial growth step enhanced the strain relaxation from the lattice mismatch at the expense of the formation of high density of misfit dislocations. By varying the thickness of the first layer, different strain states of the films were systematically achieved while keeping the total film thickness unchanged. This allowed the study of the effect of strain on permittivity, and showed good agreement with theoretical predictions. Further more, the two-step growth technique suppressed significantly the threading dislocation density in the film, the dislocations being confined to the first layer. This in turn caused reduction in the extrinsic dielectric loss at microwave frequency. The loss reduction was analyzed and explained based on a dielectric composite model.

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