Strain relaxation and threading dislocation density in helium-implanted and annealed Si1−xGex/Si(100) heterostructures

2004 ◽  
Vol 95 (10) ◽  
pp. 5347-5351 ◽  
Author(s):  
J. Cai ◽  
P. M. Mooney ◽  
S. H. Christiansen ◽  
H. Chen ◽  
J. O. Chu ◽  
...  
Keyword(s):  
Dislocation Density ◽  
Strain Relaxation ◽  
Threading Dislocation ◽  
Threading Dislocation Density

Dependence of Threading Dislocation Density on Substrate Misorientation in In0.15Ga0.85As Grown on GaAs(100)

1989 ◽  
Vol 145 ◽  
Author(s):  
P.N. Uppal ◽  
J.S. Ahearn ◽  
R. Herring
Keyword(s):  
Dislocation Density ◽  
Strain Relaxation ◽  
Dislocation Network ◽  
Uniform Density ◽  
Threading Dislocation ◽  
Dislocation Mobility ◽  
Transmission Electron ◽  
Dislocation Arrays ◽  
Threading Dislocation Density ◽  
Strained Layer Superlattices

AbstractThe density and arrangement of dislocations in In0.15Ga0.85As grown on GaAs(100)) were determined by transmission electron microscopy as a function of misorientation toward (111)A, (111)B, and (110). Strained layer superlattices were used in all cases to reduce dislocation density. Layers grown on exact GaAs(100) exhibited a non-uniform threading dislocation dis- tribution whereby some areas had a high density (∼ 109cm-2or higher) of dislocation tangles and other areas that we in between had a more uniform density (∼ 2 x 107cm-2). The misorientated layers exhibited a uniform threading dislocation distribution with densities of ∼ 5 x 106 cm-2 for (100) misoriented towards (111)A, ∼ 1 x 107cm-2towards (111)B, and ∼ 3 x 107cm-2 towards (110). The misfit dislocation network (dislocations located at the GaAs-InO0.15Ga0.85 As interface) formed orthogonal dislocation arrays in the case of exact (100) substrates and slightly non-ortho- gonal arrays in the case of misoriented substrates. These results are explained with the help of a general glide model of strain relaxation in which the exact (100) orientation has eight equally stressed glide systems which presumably activate during strain relaxation. With misoriented substrates the stress symmetry is broken and fewer glide systems experience the maximum stress, thus reducing the number of active dislocation systems. A small asymmetry in interfacial dis- location density was observed in all the cases where the linear dislocation density along the two (011) and (011) orthogonal directions differed by about 20%. This is explained by the preferred activation of (x-dislocations (high dislocation mobility) over 13-dislocations (low dislocation mobility).

scholarly journals Single-Crystalline Si1−xGex (x = 0.5~1) Thin Films on Si (001) with Low Threading Dislocation Density Prepared by Low Temperature Molecular Beam Epitaxy

2019 ◽  
Vol 9 (9) ◽  
pp. 1772
Author(s):  
Gu ◽  
Zhao ◽  
Ye ◽  
Deng ◽  
Lu
Keyword(s):  
Thin Films ◽  
Molecular Beam Epitaxy ◽  
Low Temperature ◽  
Dislocation Density ◽  
Molecular Beam ◽  
Strain Relaxation ◽  
Relaxation Mechanism ◽  
Threading Dislocation ◽  
Threading Dislocation Density ◽  
Typical Strain

Single-crystalline Si1−xGex thin films on Si (100) with low threading dislocation density (TDD) are highly desired for semiconductor industrials. It is challenging to suppress the TDD since there is a large mismatch (4.2%) between Ge and Si—it typically needs 106–107/cm2 TDD for strain relaxation, which could, however, cause device leakage under high voltage. Here, we grew Si1−xGex (x = 0.5–1) films on Si (001) by low temperature molecular beam epitaxy (LT-MBE) at 200 °C, which is much lower than the typical temperature of 450–600 °C. Encouragingly, the Si1−xGex thin films grown by LT-MBE have shown a dramatically reduced TDD down to the 103–104/cm2 level. Using transmission electron microscopy (TEM) with atomic resolution, we discovered a non-typical strain relaxation mechanism for epitaxial films grown by LT-MBE. There are multiple-layered structures being introduced along out-of-plane-direction during film growth, effectively relaxing the large strain through local shearing and subsequently leading to an order of magnitude lower TDD. We presented a model for the non-typical strain relaxation mechanism for Si1−xGex films grown on Si (001) by LT-MBE.

In Situ Study of Isothermal Strain Relaxation in Si-Ge Heteroepitaxial Films Using Substrate Curvature Measurements

1991 ◽  
Vol 239 ◽  
Author(s):  
Véronique T. Gillard ◽  
David B. Noble ◽  
William D. Nix
Keyword(s):  
Dislocation Density ◽  
Laser Scanning ◽  
Isothermal Annealing ◽  
Strain Relaxation ◽  
Threading Dislocation ◽  
Relaxation Measurements ◽  
Threading Dislocation Density ◽  
Device Applications ◽  
Curvature Measurements

ABSTRACTUnderstanding die kinetics and mechanisms of strain relaxation in Si-Ge heteroepitaxial films is pertinent to several device applications. In this paper we present a method for determining the evolution of the mobile dislocation density with time during the course of strain relaxation taking place in an isothermal annealing experiment.Wafer curvature measurements using a laser scanning technique are used to determine the elastic strain after growth in films of variable thickness and to follow the strain relaxation during isothermal annealing experiments. By coupling the strain relaxation measurements with previous TEM measurements of dislocation velocities in this system, the mobile threading dislocation density and its evolution with time are determined.

Reduction of threading dislocation density in SiGe layers on Si (001) using a two-step strain–relaxation procedure

2001 ◽  
Vol 79 (21) ◽  
pp. 3398-3400 ◽  
Author(s):  
Akira Sakai ◽  
Ken Sugimoto ◽  
Takeo Yamamoto ◽  
Masahisa Okada ◽  
Hiroya Ikeda ◽  
...  
Keyword(s):  
Dislocation Density ◽  
Strain Relaxation ◽  
Threading Dislocation ◽  
Threading Dislocation Density ◽  
Relaxation Procedure ◽  
Step Strain

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.

Influence of He implantation conditions on strain relaxation and threading dislocation density in Si0.8Ge0.2 virtual substrates

2004 ◽  
Vol 809 ◽  
Author(s):  
J. Cai ◽  
P. M. Mooney ◽  
S. H. Christiansen ◽  
H. Chen ◽  
J. O. Chu ◽  
...  
Keyword(s):  
Dislocation Density ◽  
Strong Correlation ◽  
Strain Relaxation ◽  
Sige Layer ◽  
Relaxation Mechanism ◽  
Similar Degree ◽  
Threading Dislocation ◽  
Implantation Depth ◽  
Wide Range ◽  
Threading Dislocation Density

ABSTRACTThe strain relaxation and threading dislocation density of He-implanted and annealed SiGe/Si heterostructures have been studied. For He doses above a threshold of 8×1015 cm−2, the degree of strain relaxation depends primarily on the SiGe layer thickness; a similar degree of strain relaxation is obtained when the He dose and energy are varied over a relatively wide range. In contrast, the threading dislocation density is strongly influenced by the implantation depth. There is a strong correlation between the parameter He(SiGe), the He dose in the SiGe layer calculated from He profiles simulated using the program Stopping and Range of Ions in Matter (SRIM), and the threading dislocation density. We find that to achieve a low threading dislocation density, <5×107 cm−2, He(SiGe) must be less than 1015 cm−2. The strain relaxation mechanism is also discussed.

High-Irradiance Degradation Studies of Metamorphic 1eV GaInAs Solar Cells

2012 ◽  
Vol 1432 ◽  
Author(s):  
Ryan M. France ◽  
Myles A. Steiner
Keyword(s):  
Solar Cells ◽  
Active Region ◽  
Dislocation Density ◽  
Dark Current ◽  
Degradation Mechanism ◽  
Control Cell ◽  
High Irradiance ◽  
Threading Dislocation ◽  
Threading Dislocation Density ◽  
Degradation Studies

ABSTRACTInitial tests are performed regarding the degradation of lattice-mismatched GaInAs solar cells. 1eV metamorphic GaInAs solar cells with 1-2×106 cm-2 threading dislocation density in the active region are irradiated with an 808 nm laser for 2 weeks time under a variety of temperature and illumination conditions. All devices show a small degradation in Voc that is logarithmic with time. The absolute loss in performance after 2 weeks illuminated at 1300 suns equivalent and 125°C is 7 mV Voc and 0.2% efficiency, showing these devices to be relatively stable. The dark current increases with time and is analyzed with a two-diode model. A GaAs control cell degrades at the same rate, suggesting that the observed degradation mechanism is not related to the additional dislocations in the GaInAs devices.

Relationship between misfit-dislocation formation and initial threading-dislocation density in GaInN/GaN heterostructures

2015 ◽  
Vol 54 (11) ◽  
pp. 115501 ◽  
Author(s):  
Motoaki Iwaya ◽  
Taiji Yamamoto ◽  
Daisuke Iida ◽  
Yasunari Kondo ◽  
Mihoko Sowa ◽  
...  
Keyword(s):  
Dislocation Density ◽  
Misfit Dislocation ◽  
Threading Dislocation ◽  
Threading Dislocation Density ◽  
Dislocation Formation
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