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.

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 in epitaxialCaF2,BaF2/CaF2, and PbSe/BaF2/CaF2layers on Si(111) after many temperature cycles

1994 ◽  
Vol 50 (15) ◽  
pp. 10801-10810 ◽  
Author(s):  
H. Zogg ◽  
S. Blunier ◽  
A. Fach ◽  
C. Maissen ◽  
P. Müller ◽  
...  
Keyword(s):  
Strain Relaxation ◽  
Thermal Mismatch ◽  
Temperature Cycles ◽  
Mismatch Strain

MO-CVD GaAs Grown by Direct Deposition on Si

1987 ◽  
Vol 91 ◽  
Author(s):  
S. M. Vernon ◽  
S. J. Pearton ◽  
J. M. Gibson ◽  
R. Caruso ◽  
C. R. Abernathy ◽  
...  
Keyword(s):  
Chemical Vapor ◽  
Gaas Layer ◽  
Threading Dislocation ◽  
X Ray Diffraction ◽  
Si Substrates ◽  
Transmission Electron ◽  
Activation Data ◽  
Threading Dislocation Density ◽  
Donor Activity

ABSTRACTGaAs layers were grown directly on misoriented (2° off (100)→[011]) Si substrates by Metalorganic Chemical Vapor Deposition. The threading dislocation density at the surface of 4 μm thick layers was typically 108cm−2, as determined by both preferential etching and transmission electron microscopy. Rapid thermal annealing (900°C, 10s) improved the crystalline quality of the GaAs near the heterointerface while allowing no detectable Si diffusion into this layer. Two deep electron traps were observed in the undoped GaAs, but were present at a low concentration (∼ 1013 cm−3 ). The (400) x-ray diffraction peak width from the GaAs was significantly reduced with increasing GaAs layer thickness, indicating improved material quality. This is supported by Si implant activation data, which shows higher net donor activity in thicker layers.

Improved Structural Quality and Carrier Decay Times in GaN Epitaxy on SiN and TiN Porous Network Templates

2006 ◽  
Vol 527-529 ◽  
pp. 1505-1508
Author(s):  
Ümit Özgür ◽  
Y. Fu ◽  
Cole W. Litton ◽  
Y.T. Moon ◽  
F. Yun ◽  
...  
Keyword(s):  
Chemical Vapor ◽  
Structural Quality ◽  
Threading Dislocation ◽  
X Ray Diffraction ◽  
Porous Network ◽  
X Ray ◽  
Radiative Efficiency ◽  
Decay Times ◽  
Threading Dislocation Density

Improved structural quality and radiative efficiency were observed in GaN thin films grown by metalorganic chemical vapor deposition on in situ-formed SiN and TiN porous network templates. The room temperature carrier decay time of 1.86 ns measured for a TiN network sample is slightly longer than that for a 200 μm-thick high quality freestanding GaN (1.73 ns). The linewidth of the asymmetric X-Ray diffraction (XRD) (1012) peak decreases considerably with the use of SiN and TiN layers, indicating the reduction in threading dislocation density. However, no direct correlation is yet found between the decay times and the XRD linewidths, suggesting that point defect and impurity related nonradiative centers are the main parameters affecting the lifetime.

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.

Impact of the Growth Parameters on the Structural Properties of Si0.8Ge0.2 Virtual Substrates

2005 ◽  
Vol 108-109 ◽  
pp. 445-450 ◽  
Author(s):  
Y. Bogumilowicz ◽  
J.M. Hartmann ◽  
F. Laugier ◽  
G. Rolland ◽  
Thierry Billon
Keyword(s):  
Growth Rate ◽  
Structural Properties ◽  
Growth Parameters ◽  
Strain Relaxation ◽  
Chemical Vapour ◽  
Root Mean Square Roughness ◽  
Threading Dislocation ◽  
Reduced Pressure ◽  
Threading Dislocation Density ◽  
The Impact

We have focused in this paper on the impact of the growth rate and of the grading rate on the structural properties of Si0.8Ge0.2 virtual substrates grown at 900°C in a commercial reduced pressure chemical vapour deposition reactor. Adopting a grading rate of 4% Ge / $m together with a growth rate around 140 nm min.-1 yields very high quality Si0.8Ge0.2 virtual substrates. Their macroscopic degree of strain relaxation is indeed very close to 100%, their surface root mean square roughness is around 2.3 nm and most importantly their field threading dislocation density is of the order of 6x104 cm-2 only, with almost no pile-ups.

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.

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