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.

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.

Thermal Mismatch Strain Relaxation Mechanisms and Hysteresis in Pb1−SnxSe-on-CaF2/Si Structures

1995 ◽  
Vol 379 ◽  
Author(s):  
H. Zogg ◽  
P. Müller ◽  
A. Fach ◽  
J. John ◽  
C. Paglino ◽  
...  
Keyword(s):  
Strain Relaxation ◽  
Structural Quality ◽  
Threading Dislocation ◽  
Misfit Dislocations ◽  
Thermal Mismatch ◽  
Mismatch Strain ◽  
Threading Dislocation Density ◽  
Deformation Hardening ◽  
Interaction Probability

ABSTRACTThe strain induced by the thermal mismatch in Pbl−xSnxSe and other IV–VI compound layers on Si(111)-substrates relaxes by glide of dislocations in the main <110> {001}-glide system. The glide planes are arranged with 3-fold symmetry and inclined to the (111)-surface. Despite a high threading dislocation density (> 107 cm−2) in these heavily lattice mismatched structures, the misfit dislocations move easily even at cryogenic temperatures and after many temperature cycles between RT and 77K. The cumulative plastic deformation after these cycles is up to 500%! Despite a pronounced deformation hardening occurs, the structural quality of the layer is only slightly adversely affected as regards additional threading dislocations created. The interaction probability between these dislocations is estimated to be about 10−5.

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.

Planar Defects, Voids and their Relationship in 3C-SiC Layers

2005 ◽  
Vol 483-485 ◽  
pp. 189-192
Author(s):  
David Méndez ◽  
A. Aouni ◽  
Daniel Araújo ◽  
Gabriel Ferro ◽  
Yves Monteil ◽  
...  
Keyword(s):  
Cross Section ◽  
Lattice Mismatch ◽  
Misfit Dislocations ◽  
Lateral Growth ◽  
Si Substrate ◽  
Transmission Electron Microscopy Micrographs ◽  
Planar Defects ◽  
Transmission Electron ◽  
The Relationship

One of the problems with Si(001)/3C-SiC templates is that they involve highly defective interfaces due to the presence of misfit dislocations, voids and planar defects that degrade the SiC layer quality. A way to accommodate the high lattice mismatch between these materials and reduce the voids density is to carbonize the Si substrate before the epitaxial growth. In this contribution an alternative way to reduce planar defects density is presented by analyzing the relationship between planar defects and voids. Planar view and cross section transmission electron microscopy micrographs show a diminution of planar defects in the regions surrounding the voids. Due to the lower elastic energy over the voids and/or to a lateral growth in these regions, the generation of planar defects is partially deactivated, improving locally the crystalline quality of the SiC layer. The introduction of such cavities can be thus seen as a new parameter of Si/SiC templates design.

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.

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.

Photoluminescence, Raman Scattering and Rbs/Channeling of Epitaxial Fluorides

1985 ◽  
Vol 60 ◽  
Author(s):  
W.J. Choyke ◽  
J.L. Bradshaw ◽  
A. Mascarenhas ◽  
Z.C. Feng ◽  
S. Sinharoy ◽  
...  
Keyword(s):  
Low Temperature ◽  
Raman Scattering ◽  
Stress Disorder ◽  
Lattice Mismatch ◽  
Growth Conditions ◽  
Diagnostic Techniques ◽  
High Quality ◽  
Crystalline Films ◽  
Film Substrate

AbstractGrowth conditions are described for producing high quality crystalline films of CaF2 on (100) and (111) GaAs and LaF3, CeF3 and NdF3 on (111) Si. Rutherford backscattering/channeling, low temperature (<2K) photolumin-escence and Raman scattering are used as diagnostic techniques to probe the crystalline quality of the films and the stress/disorder induced at the film-substrate interface due to lattice mismatch.

Large Lattice Mismatch Epitaxy

1995 ◽  
Vol 410 ◽  
Author(s):  
S. Mahajan
Keyword(s):  
Self Assembly ◽  
Lattice Mismatch ◽  
Interface Energy ◽  
Threading Dislocation ◽  
Threading Dislocations ◽  
Misfit Dislocations ◽  
Island Growth ◽  
First Case ◽  
Novel Approach ◽  
Large Lattice Mismatch

ABSTRACTDuring the early stages of lattice mismatch epitaxy, island growth is observed in several systems. The evolution of this morphology is attributed to a large value of the substrate/layer interface energy. Origins of misfit and threading dislocations are also considered. Nucleation of misfit dislocations could occur either from steps present on surfaces of islands or from substrate/island edges. Arms of glide loops terminating at the surface in the first case form threading segments in the layer, whereas the coalescence of islands in which misfit dislocations are not aligned with respect to each other lead to threading dislocations in the second case. Existing approaches for lowering threading dislocation densities are also evaluated. A novel approach involving controlled, self-assembly of islands is presented to achieve the preceding objective.

Heteroepitaxy of GaAs, GaP and InP on Si By Omvpe and Their Application to thin Film Solar Cells

1988 ◽  
Vol 116 ◽  
Author(s):  
Akio Yamamoto ◽  
Safumi Yamaguchi
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Lattice Mismatch ◽  
Defect Density ◽  
Growth Parameters ◽  
Misfit Dislocations ◽  
Thermally Induced ◽  
Growth Method ◽  
Step Growth ◽  
Residual Strains

AbstractOrganometallic vapor phase epitaxial (OMVPE) growth of GaAs, GaP and InP on Si has been studied using the two-step growth method. Growth parameters for a heteroepitaxial film with a specular surface, a single-domain structure and high crystallinity are demonstrated and discussed. Residual strains in grown films are evaluated and analyzed by taking account of elastic lattice deformation due to lattice mismatch or thermally- induced strain accomodation by rearrangement of misfit dislocations. Thin film GaAs and InP solar cells are fabricated and their performances are discussed in relation to defect density in the films. For GaAs cells, an efficiency of 18 % (AM1.5, active area) is attained by reducing defect density to 2×106 >cm−2 . The defect density is ~. 5×107 cm−2 in the present InP films, and is needed to be less than 106 cm−2 to attain an efficiency of 18 %.

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