Study of thermal strain relaxation in GaAs grown on Ge/Si substrates

2006 ◽  
Vol 121 (2) ◽  
pp. 375-378 ◽  
Author(s):  
D. Colombo ◽  
E. Grilli ◽  
M. Guzzi ◽  
S. Sanguinetti ◽  
A. Fedorov ◽  
...  
Keyword(s):  
Strain Relaxation ◽  
Thermal Strain ◽  
Si Substrates

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.

Ultra-thin strain relaxed SiGe buffer layers with 40% Ge

2004 ◽  
Vol 809 ◽  
Author(s):  
Klara Lyutovich ◽  
Erich Kasper ◽  
Michael Oehme
Keyword(s):  
Surface Morphology ◽  
Point Defect ◽  
Strain Relaxation ◽  
Layer Growth ◽  
Buffer Layers ◽  
In Situ Monitoring ◽  
Process Window ◽  
Growth Stages ◽  
Growth Monitoring ◽  
Si Substrates

ABSTRACTVirtual substrates with ultra-thin SiGe strain relaxed buffers have been grown on Si substrates by a method employing point defect supersaturation in the growing layers. A concept of the point defect influence on the strain relaxation and on defect interactions in layers has been proposed. A method is developed to increase the degree of relaxation in sub-100 nm SiGe buffer layers and to provide a smooth surface morphology. Layer growth has been realized by solid source molecular beam epitaxy in a chamber equipped with an in situ monitoring system. One of the growth stages, performed at a very low temperature, serves the generation of point defects. Strain relaxation tunable up to the high degree and a crosshatch-free surface morphology are demonstrated in 40nm thick SiGe buffers which contain 40-45% Ge.Growth monitoring enables the control of the process window and the layer crystallization by a chosen mechanism.Virtual substrates produced by the described method were successfully tested in nMODFET structures.

Crosshatch patterns in GaAs films on Si substrates due to thermal strain in annealing processes

1987 ◽  
Vol 51 (23) ◽  
pp. 1928-1930 ◽  
Author(s):  
Takashi Nishioka ◽  
Yoshio Itoh ◽  
Akio Yamamoto ◽  
Masafumi Yamaguchi
Keyword(s):  
Thermal Strain ◽  
Si Substrates ◽  
Gaas Films

Elastic Strain Relaxation in Si1-xGex Layers Epitaxially Grown on Si Substrates

1998 ◽  
Vol 05 (01) ◽  
pp. 133-138 ◽  
Author(s):  
I. Berbezier ◽  
B. Gallas ◽  
J. Derrien
Keyword(s):  
Elastic Constants ◽  
Elastic Strain ◽  
Lattice Mismatch ◽  
Strain Relaxation ◽  
Experimental Conditions ◽  
Si Substrates ◽  
Critical Lattice ◽  
Convergent Beam ◽  
Plane View

We have investigated the elastic strain relaxation in Si 1-x Ge x layers grown by the molecular beam epitaxy (MBE) technique and in situ controlled with RHEED. Up to ≈0.8% critical lattice mismatch (about 20% Ge) uniform strained and flat layers were grown both on (111) and on (001) Si substrates. Calculations of the elastic constants evidenced a tetragonal distortion about 50% higher on (001) than on (111) in the same experimental conditions. At higher misfits (and/or thicknesses) a growth instability was evidenced only on (001) Si substrates. Si 1-x Ge x layers there displayed a surface layer undulation. On the contrary, Si 1-x Ge x layers grown on (111) Si substrates remained smooth throughout the growth up to the plastic relaxation of the layers. To determine stress fields in the Si 1-x Ge x layers, a high spatial resolution convergent beam electron diffraction (CBED) experiment was performed with a field effect analytical microscope. The CBED technique was applied to two typical cases: totally strained layer and undulated dislocation-free layer. In the latter case, CBED patterns recorded on nanometer scale areas of an undulation crest (cross-section sample) showed a gradual elastic relaxation mainly directed along the growth axis (z). Moreover a triclinic distortion of the unit cell was pointed out. These results were confirmed on a plane view sample. In conclusion, our results show that the driving force for the undulation is not the in-plane elastic relaxation since CBED experiments proved an important elastic relaxation of the (001) Si 1-x Ge x layers along the z axis. This was in agreement with the calculations of the elastic constants. We think that this could be at the origin of the undulation.

scholarly journals Lattice bending in three-dimensional Ge microcrystals studied by X-ray nanodiffraction and modelling

2016 ◽  
Vol 49 (3) ◽  
pp. 976-986 ◽  
Author(s):  
Mojmír Meduňa ◽  
Claudiu Valentin Falub ◽  
Fabio Isa ◽  
Anna Marzegalli ◽  
Daniel Chrastina ◽  
...  
Keyword(s):  
Crystal Lattice ◽  
Strain Relaxation ◽  
Thermal Strain ◽  
Three Dimensional ◽  
The Finite Element Method ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Microelectronic Devices ◽  
Expansion Coefficients ◽  
Diffraction Patterns

Extending the functionality of ubiquitous Si-based microelectronic devices often requires combining materials with different lattice parameters and thermal expansion coefficients. In this paper, scanning X-ray nanodiffraction is used to map the lattice bending produced by thermal strain relaxation in heteroepitaxial Ge microcrystals of various heights grown on high aspect ratio Si pillars. The local crystal lattice tilt and curvature are obtained from experimental three-dimensional reciprocal space maps and compared with diffraction patterns simulated by means of the finite element method. The simulations are in good agreement with the experimental data for various positions of the focused X-ray beam inside a Ge microcrystal. Both experiment and simulations reveal that the crystal lattice bending induced by thermal strain relaxation vanishes with increasing Ge crystal height.

scholarly journals GaAs epilayers grown on patterned (001) silicon substrates via suspended Ge layers

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Andrea Ballabio ◽  
Sergio Bietti ◽  
Andrea Scaccabarozzi ◽  
Luca Esposito ◽  
Stefano Vichi ◽  
...  
Keyword(s):  
Molecular Beam ◽  
Thermal Strain ◽  
Gaas Layer ◽  
Optical Quality ◽  
Silicon Substrates ◽  
Phase Boundaries ◽  
High Optical Quality ◽  
Quantum Well Structures ◽  
Si Substrates

AbstractWe demonstrate the growth of low density anti-phase boundaries, crack-free GaAs epilayers, by Molecular Beam Epitaxy on silicon (001) substrates. The method relies on the deposition of thick GaAs on a suspended Ge buffer realized on top of deeply patterned Si substrates by means of a three-temperature procedure for the growth. This approach allows to suppress, at the same time, both threading dislocations and thermal strain in the epilayer and to remove anti-phase boundaries even in absence of substrate tilt. Photoluminescence measurements show the good uniformity and the high optical quality of AlGaAs/GaAs quantum well structures realized on top of such GaAs layer.

scholarly journals Strain Relaxation and Induced Defects in SiGe Thin Films Grown on Ion-Implanted Si Substrates

2004 ◽  
Vol 45 (8) ◽  
pp. 2644-2646 ◽  
Author(s):  
Junji Yamanaka ◽  
Kentaro Sawano ◽  
Kiyokazu Nakagawa ◽  
Kumiko Suzuki ◽  
Yusuke Ozawa ◽  
...  
Keyword(s):  
Thin Films ◽  
Strain Relaxation ◽  
Si Substrates ◽  
Induced Defects ◽  
Ion Implanted
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