Lattice Engineering Using Lateral Oxidation of Alas: an Approach to Generate Substrates With New Lattice Constants

1998 ◽  
Vol 535 ◽  
Author(s):  
P.M. Chavarkar ◽  
L. Zhao ◽  
S. Keller ◽  
K.A. Black ◽  
E. Hu ◽  
...  
Keyword(s):  
Strain Relaxation ◽  
Local Strain ◽  
Epitaxial Layers ◽  
Threading Dislocation ◽  
Misfit Dislocations ◽  
Reactive Material ◽  
New Approach ◽  
Lattice Constants ◽  
Lateral Oxidation ◽  
Threading Dislocation Density

AbstractWe demonstrate a new approach to the growth of dislocation free lattice-mismatched materials on GaAs substrates using Al2O3 interlayers obtained by lateral oxidation of AlAs. This is achieved by generating relaxed low threading dislocation density InGaAs templates which are mechanically supported but epitaxially decoupled from the host GaAs substrate. This process uses the phenomena of relaxation of strained coherent hypercritical thickness (h > hcritical,) layer in direct contact with an oxidizing Al-containing semiconductor (i.e. AlAs or AlGaAs). 5000 Å In0.11Ga0.89As layers were then grown on the In0.2 Ga0.8As/Al2O3/GaAs template which acts as a pseudo-substrate (lattice-engineered substrate). The epitaxial layers are partially relaxed and have extremely smooth surface morphology. Further TEM micrographs of these epitaxial layers show no misfit dislocations or related localized strain fields at the In0.2Ga0.8As/Al2O3 interface. The absence of misfit dislocations or local strain contrast at the In0.2Ga0.8As/Al2O3 interface is attributed to both reactive material removal during the oxidation process and the porous nature of the oxide itself. We propose that the strain relaxation in In0.3Ga0.7As is enhanced due to the absence of misfit dislocations at the In0.2Ga0.8As/A12O3 interface.

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.

The use of ion implantation and annealing for the fabrication of strained silicon on thin SiGe virtual substrates

2004 ◽  
Vol 809 ◽  
Author(s):  
D. Buca ◽  
M.J. Mörschbächer ◽  
B. Holländer ◽  
M. Luysberg ◽  
R. Loo ◽  
...  
Keyword(s):  
Ion Implantation ◽  
Rutherford Backscattering Spectrometry ◽  
Strain Relaxation ◽  
Chemical Vapor ◽  
Implantation Dose ◽  
Threading Dislocation ◽  
Misfit Dislocations ◽  
Dislocation Loops ◽  
Strained Si ◽  
Threading Dislocation Density

ABSTRACTStrain relaxed Si1−xGex layers are attractive virtual substrates for the epitaxial growth of strained Si. Tensile strained Si has attracted a lot of attention due its superior electronic properties. In this study, the strain relaxation of pseudomorphic Si1−xGex layers grown by chemical vapor deposition (CVD) on Si(100) substrates was investigated after He+ ion implantation and thermal annealing. The implantation induced defects underneath the SiGe/Si interface promote strain relaxation during annealing via preferred nucleation of dislocation loops which form misfit dislocations at the interface to the substrate. The amount of strain relaxation as well as the final threading dislocation density depend on the implantation dose and energy. Si1−xGex layers with thicknesses between 75 and 420 nm and Ge concentrations between 19 and 29 at% were investigated. The strain relaxation strongly depends on the layer thickness. Typically the structures show ≈70 % strain relaxation and threading dislocation densities in the low 106 cm−2 range. AFM investigations proved excellent surface morphology with an rms roughness of 0.6 nm. The samples were investigated by Rutherford backscattering spectrometry, ion channeling, transmission electron microscopy and atomic force microscopy.

Role of Dislocation Interactions in Decreasing Mobile Threading Dislocation Density and Limiting Strain Relaxation in Si1-xGex Heteroepitaxial Films

1994 ◽  
Vol 356 ◽  
Author(s):  
Veronique T Gillard ◽  
William D Nix
Keyword(s):  
Dislocation Density ◽  
Late Stage ◽  
Strain Relaxation ◽  
Threading Dislocation ◽  
Misfit Dislocations ◽  
Si Substrates ◽  
Good Account ◽  
Dislocation Interactions ◽  
Threading Dislocation Density ◽  
Residual Strains

AbstractIn situ substrate curvature measurements obtained during isothermal annealing of Si1-xGex films grown on (001) Si substrates allow determination of the evolution of strain versus time in these films. By coupling the strain relaxation measurements with previous measurements of dislocation velocities in this system, the mobile threading dislocation density and its evolution in the course of strain relaxation can be determined. The results indicate that in the late stage of strain relaxation, the mobile threading dislocation density decreases significantly. Results obtained with samples of two different sizes show that this decrease in mobile dislocation density is not primarily associated with dislocations running out at the edges of the film but with dislocation interactions impeding their further motion. Furthermore, for films thinner than 500 nm the residual strains after annealing are significantly higher than the values predicted by the equilibrium theory of misfit dislocations. The measured residual strains are compared with predictions based on Freund’s treatment of the blocking of a moving threading segment by an orthogonal misfit dislocation in its path. We find that the blocking criterion gives a very good account of the residual strain in Si1-xGex films and that blocking of threading dislocations by other misfit dislocations appears to play an important role in the late stage of strain relaxation.

Stress Relaxation in Uniquely Oriented SiGe/Si Epitaxial Layers

1999 ◽  
Vol 594 ◽  
Author(s):  
M. E. Ware ◽  
R. J. Nemanich
Keyword(s):  
Stress Relaxation ◽  
Surface Morphology ◽  
Strain Relaxation ◽  
Epitaxial Layers ◽  
Misfit Dislocations ◽  
Strained Layers ◽  
Force Microscopy ◽  
Si Substrates ◽  
Atomic Force ◽  
Deposited Films

AbstractThis study explores stress relaxation of epitaxial SiGe layers grown on Si substrates with unique orientations. The crystallographic orientations of the Si substrates used were off-axis from the (001) plane towards the (111) plane by angles, θ = 0, 10, and 22 degrees. We have grown 100nm thick Si(1−x) Ge(x) epitaxial layers with x=0.3 on the Si substrates to examine the relaxation process. The as-deposited films are metastable to the formation of strain relaxing misfit dislocations, and thermal annealing is used to obtain highly relaxed films for comparison. Raman spectroscopy has been used to measure the strain relaxation, and atomic force microscopy has been used to explore the development of surface morphology. The Raman scattering indicated that the strain in the as-deposited films is dependent on the substrate orientation with strained layers grown on Si with 0 and 22 degree orientations while highly relaxed films were grown on the 10 degree substrate. The surface morphology also differed for the substrate orientations. The 10 degree surface is relatively smooth with hut shaped structures oriented at predicted angles relative to the step edges.

Reduction in threading dislocation density in ge epitaxial layers grown on Si(001) substrates by using rapid thermal annealing

2015 ◽  
Vol 67 (9) ◽  
pp. 1646-1650 ◽  
Author(s):  
Keun Wook Shin ◽  
Sung Hyun Park ◽  
Sehun Park ◽  
Euijoon Yoon ◽  
Sewoung Oh ◽  
...  
Keyword(s):  
Dislocation Density ◽  
Thermal Annealing ◽  
Rapid Thermal Annealing ◽  
Epitaxial Layers ◽  
Threading Dislocation ◽  
Threading Dislocation Density

A Multiplication Mechanism for Misfit Dislocations

1992 ◽  
Vol 263 ◽  
Author(s):  
Michael A. Capano
Keyword(s):  
Dislocation Loop ◽  
Misfit Dislocation ◽  
Epitaxial Layers ◽  
Threading Dislocation ◽  
Misfit Dislocations ◽  
Sequential Process ◽  
Single Dislocation ◽  
Dislocation Arrays ◽  
Half Loop ◽  
Dislocation Sources

ABSTRACTA new mechanism which describes how misfit dislocations in epitaxial layers multiply is presented. This work demonstrates how a single threading dislocation can give rise to an array of dislocation sources, where each source generates a single dislocation loop perpendicular to the primary misfit dislocation. As a threading dislocation with pure screw character glides through an epilayer, certain processes occur which lead to the production of a single dislocation half-loop, and the regeneration of the original threading dislocation. The regenerated threading dislocation continues to propagate on its primary glide plane, which allows the process to repeat itself at some later time. The result of this sequential process is an array of half-loops perpendicular to the primary misfit dislocation. The shape and symmetry of the arrays also contains information regarding how the mechanism operates. The proposed mechanism is related to misfit dislocation arrays in a single Si0.87Ge0.13 layer on Si(001).

Determination of threading dislocation density in hetero-epitaxial layers by diffuse X-ray scattering

1995 ◽  
Vol 28 (4A) ◽  
pp. A114-A119 ◽  
Author(s):  
E Koppensteiner ◽  
A Schuh ◽  
G Bauer ◽  
V Holy ◽  
G P Watson ◽  
...  
Keyword(s):  
Dislocation Density ◽  
Epitaxial Layers ◽  
Threading Dislocation ◽  
X Ray ◽  
X Ray Scattering ◽  
Threading Dislocation Density ◽  
Ray Scattering

Mechanism for the Reduction of Threading Dislocation Densities in Si0.82Ge0.18 Films on Silicon on Insulator Substrates

2001 ◽  
Vol 673 ◽  
Author(s):  
E.M. Rehder ◽  
T.S. Kuan ◽  
T.F. Kuech
Keyword(s):  
Dislocation Density ◽  
Chemical Vapor ◽  
Dislocation Core ◽  
Extensive Study ◽  
Silicon On Insulator ◽  
Dislocation Dynamics ◽  
Threading Dislocation ◽  
Misfit Dislocations ◽  
Threading Dislocation Density ◽  
Soi Substrates

ABSTRACTWe have made an extensive study of Si0.82Ge0.18 film relaxation on silicon on insulator (SOI) substrates having a top Si layer 40, 70, 330nm, and 10[.proportional]m thick. SiGe films were deposited with a thickness up to 1.2[.proportional]m in an ultrahigh vacuum chemical vapor deposition system at 630°C. Following growth, films were characterized by X-ray diffraction and a dislocation revealing etch. The same level of relaxation is reached for each thickness of SiGe film independent of the substrate structure. Accompanying the film relaxation is the development of a tetragonal tensile strain in the thin Si layer of the SOI substrates. This strain reached 0.22% for the 1.2[.proportional]m film on the 40nm SOI and decreases with SOI thickness. The Si thickness of the SOI substrate also effected the threading dislocation density. For 85% relaxed films the density fell from 7×106 pits/cm2 on bulk Si to 103pits/cm2 for the 40, 70, and 330nm SOI substrates. The buried amorphous layer of the SOI substrate alters the dislocation dynamics by allowing dislocation core spreading or dislocation dissociation. The reduced strain field of these dislocations reduces dislocation interactions and the pinning that results. Without the dislocation pinning, the misfit dislocations can extend longer distances yielding a greatly reduced threading dislocation density.

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