Tilts in Thin Strained Layers.

1991 ◽  
Vol 238 ◽  
Author(s):  
Richard Beanland
Keyword(s):  
Band Gap ◽  
Misfit Dislocation ◽  
Side Effect ◽  
Epitaxial Films ◽  
Misfit Dislocations ◽  
Poisson Effect ◽  
Strained Layers ◽  
Band Gap Engineering ◽  
Recent Formulation ◽  
Coherency Strains

ABSTRACTThere is considerable interest at present in the mechanisms of tilting of epitaxial films, such that low index planes in layer and substrate have slightly different orientations. There are two primary causes of this effect: a) coherency strains and b) the action of misfit dislocations. It is important to distinguish between the two effects, particularly in the case of strained layers used for band-gap engineering. Using a recent formulation of the Frank-Bilby equation for the dislocation content of interfaces, it is shown how planes may be rotated in coherent layers due to both the Poisson effect and anisotropic misfit. An advantage of the Frank-Bilby equation is that it allows consideration of semicoherent layers. It is shown that a side effect of misfit dislocation introduction can be to introduce a further rotation of the epitaxial layer. Both these effects have been measured experimentally. The amount and the sense of rotation is compared to theory.

Rapid Thermal Processing of Buried Sil−xGex Strained Layers; Photoluminescence Decay and Misfit Dislocation Generation.

1990 ◽  
Vol 198 ◽  
Author(s):  
D.C. Houghton ◽  
N.L. Rowell
Keyword(s):  
Quantum Wells ◽  
Misfit Dislocation ◽  
Thermal Processing ◽  
Internal Quantum Efficiency ◽  
Dislocation Nucleation ◽  
Multiple Quantum ◽  
Misfit Dislocations ◽  
Dislocation Generation ◽  
Strained Layers ◽  
Wide Range

ABSTRACTThe thermal constraints for device processing imposed by strain relaxation have been determined for a wide range of Si-Ge strained heterostructures. Misfit dislocation densities and glide velocities in uncapped Sil-xGex alloy layers, Sil-xGex single and multiple quantum wells have been measured using defect etching and TEM for a range of anneal temperatures (450°C-1000°C) and anneal times (5s-2000s). The decay of an intense photoluminescence peak (∼ 10% internal quantum efficiency ) from buried Si1-xGex strained layers has been correlated with the generation of misfit dislocations in adjacent Sil-xGex /Si interfaces. The misfit dislocation nucleation rate and glide velocity for all geometries and alloy compositions (0<x<0.25) were found to be thermally activated processes with activation energies of (2.5±0.2)eV and (2.3-0.65x)eV, respectively. The time-temperature regime available for thermal processing is mapped out as a function of dislocation density using a new kinetic model.

The Roles of Stress, Geometry and Orientation on Misfit Dislocations Kinetics and Energetics in Epitaxial Strained Layers.

1991 ◽  
Vol 239 ◽  
Author(s):  
R. Hull ◽  
J. C. Bean ◽  
F. Ross ◽  
D. Bahnck ◽  
L. J. Pencolas
Keyword(s):  
Misfit Dislocation ◽  
Lattice Mismatch ◽  
Strain Relaxation ◽  
Misfit Dislocations ◽  
Slip Systems ◽  
Strained Layers ◽  
Burgers Vector ◽  
Partial Dislocations ◽  
Strain Stress ◽  
Kinetics Of

ABSTRACTThe geometries, microstructures, energetics and kinetics of misfit dislocations as functions of surface orientation and the magnitude of strain/stress are investigated experimentally and theoretically. Examples are drawn from (100), (110) and (111) surfaces and from the GexSi1–x/Si and InxGa1–x/GaAs systems. It is shown that the misfit dislocation geometries and microstructures at lattice mismatch stresses < - 1GPa may in general be predicted by operation of the minimum magnitude Burgers vector slipping on the widest spaced planes. At stresses of the order several GPa, however, new dislocation systems may become operative with either modified Burgers vectors or slip systems. Dissociation of totál misfit dislocations into partial dislocations is found to play a crucial role in strain relaxation, on surfaces other than (100) under compressive stress.

Intrinsic excitonic photoluminescence and band-gap engineering of wide-gapp-type oxychalcogenide epitaxial films of LnCuOCh (Ln=La, Pr, and Nd; Ch=S or Se) semiconductor alloys

2003 ◽  
Vol 94 (9) ◽  
pp. 5805-5808 ◽  
Author(s):  
Hidenori Hiramatsu ◽  
Kazushige Ueda ◽  
Kouhei Takafuji ◽  
Hiromichi Ohta ◽  
Masahiro Hirano ◽  
...  
Keyword(s):  
Band Gap ◽  
Epitaxial Films ◽  
Semiconductor Alloys ◽  
Band Gap Engineering

Reduction of Misfit Dislocation Density in Finite Lateral Size Sil-xGex Films Grown by Selective Epitaxy

1993 ◽  
Vol 298 ◽  
Author(s):  
L. Vescan ◽  
T. Stoica ◽  
C. Dieker ◽  
H. LÜth
Keyword(s):  
Dislocation Density ◽  
Misfit Dislocation ◽  
Equilibrium Model ◽  
Size Dependence ◽  
Critical Thickness ◽  
Misfit Dislocations ◽  
Lateral Size ◽  
Relaxation Model ◽  
Main Hypothesis ◽  
Strained Layers

AbstractIn Si0.88Ge0.12/Si strained layers misfit dislocations formed during growth in small pads are generated at a significantly higher critical thickness than on extended areas, while pads of lateral size of 10 μm or smaller show no evidence of misfit dislocations at all. The SiGe layers investigated were selectively grown on patterned substrates with pad sizes from 2 μm to 1 cm. An elastic relaxation model was used to calculate the pad size dependence of the critical thickness. The main hypothesis of the model is that the density of misfit dislocations is solely affected by the elastic relaxation at the edges of small epitaxial areas. This equilibrium model is able to explain the observed absence of misfit dislocations on small pads, however it predicts a critical thickness for finite sizes much lower than the observed one.

Structure and band gap engineering of Fe-doped SrSnO 3 epitaxial films

2014 ◽  
Vol 108 (3) ◽  
pp. 37003 ◽  
Author(s):  
Qinzhuang Liu ◽  
Hong Li ◽  
Bing Li ◽  
Wei Wang ◽  
Qiangchun Liu ◽  
...  
Keyword(s):  
Band Gap ◽  
Epitaxial Films ◽  
Band Gap Engineering

A Misfit Dislocation Blocking Mechanism in Continuous InGaAs Layers Grown on Patterned GaAs

1993 ◽  
Vol 308 ◽  
Author(s):  
G. Patrick Watson ◽  
Dieter G. Ast ◽  
Timothy J. Anderson ◽  
Balu Pathangey
Keyword(s):  
Misfit Dislocation ◽  
Energy Cost ◽  
Dislocation Segment ◽  
Threading Dislocation ◽  
Misfit Dislocations ◽  
Strained Layers ◽  
Blocking Mechanism

ABSTRACTPrevious work showed that misfit dislocations were blocked at trench walls in a unique way in InGaAs strained layers grown on GaAs that was patterned and etched to form a series of mesas separated by trenches. A model is developed to explain the behavior of misfit dislocations in this material. The energy cost of extending the threading dislocation segment, which accompanies a misfit dislocation during glide, can impede the motion of these defects if the trench walls are steep enough.

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.

Misfit Dislocations in the Ilmenite (FeTiO3)-Hematite (Fe2O3) System

1980 ◽  
Vol 38 ◽  
pp. 212-213 ◽  
Author(s):  
K.P.D. Lagerlöf ◽  
A.H. Heuer ◽  
T.E. Mitchell
Keyword(s):  
Misfit Dislocation ◽  
Lattice Parameters ◽  
Dislocation Network ◽  
Misfit Dislocations ◽  
Space Group ◽  
Two Phases ◽  
Hematite Fe2o3

It has been reported by Lally et. al. [1] that precipitates of hematite (Fe2O3, space group R3c) in a matrix of ilmenite (FeTiO3, space group R3) are lens shaped and flattened along the [0001]-direction. The coherency across the interface is lost by the introduction of a misfit dislocation network, which minimizes the strain due to the deviation in lattice parameters between the two phases [2]. The purpose of this paper is to present a new analysis of this network.

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