Low Threading Dislocation Densities in Thick, Relaxed Si1−xGex Buffer Layers

1991 ◽  
Vol 220 ◽  
Author(s):  
C. G. Tuppen ◽  
C. J. Gibbings ◽  
M. Hockly
Keyword(s):  
Dislocation Density ◽  
Dislocation Nucleation ◽  
Buffer Layers ◽  
Threading Dislocation ◽  
Direct Deposition ◽  
Dislocation Densities ◽  
Defect Densities

ABSTRACTA series of relaxed Si1−xGex alloy layers with germanium contents up to 70% has been deposited on silicon. Although direct deposition ot these highly mismatched layers on silicon gave dislocation densities of 109-1010cm2 and poor morphology, it was found that the use of a linear grade enabled completely relaxed Si.3Ge.7 layers with defect densities of ∼3.105cm−2 to be obtained. However, if the grading was too rapid the dislocation density was much higher. The role of dislocation nucleation and propagation in determining the required thickness of graded layer is discussed.

Defect-Engineered Graded GexSi1-x Buffers on Si (001) with Extreme Low Threading Dislocation Density

1995 ◽  
Vol 378 ◽  
Author(s):  
G. Kissinger ◽  
T. Morgenstern ◽  
G. Morgenstern ◽  
H. B. Erzgräber ◽  
H. Richter
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Atomic Force Microscopy ◽  
Dislocation Density ◽  
Threading Dislocation ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Dislocation Densities ◽  
Threading Dislocation Density

AbstractStepwise equilibrated graded GexSii-x (x≤0.2) buffers with threading dislocation densities between 102 and 103 cm−2 on the whole area of 4 inch silicon wafers were grown and studied by transmission electron microscopy, defect etching, atomic force microscopy and photoluminescence spectroscopy.

Residual Strain and Defect Analysis in as Grown and Annealed SiGe Layers

1991 ◽  
Vol 220 ◽  
Author(s):  
A. R. Powell ◽  
R. A. Kubiak ◽  
T. E. Whall ◽  
E. H. C. Parker ◽  
D. K. Bowen
Keyword(s):  
Residual Strain ◽  
Buffer Layers ◽  
Limited Area ◽  
Threading Dislocation ◽  
Misfit Dislocations ◽  
High Temperature Anneal ◽  
Dislocation Densities ◽  
Acceptable Quality ◽  
Strained Sige

ABSTRACTIn this paper we address the problem of producing SiGe buffer layers of acceptable quality for the growth of symmetrically strained SiGe structures. Initially we consider SiGe layers grown to well beyond the metastable critical thickness and examine the degree of residual strain both as - grown and post anneal. The defect levels in metastable SiGe layers following high temperature anneal were also studied. A buffer layer was grown consisting of stacked metastable SiGe layers each of which is annealed in situ prior to the growth of the next layer and terminating with a 0.45 SiGe alloy. This produces nearly fully relaxed 1.15pim thick structures with threading dislocation densities of 4 × 106cm−2. Limited area growth on Si suggests that elastically relaxed material free of both threading and misfit dislocations can be produced.

Equilibrium Lattice Relaxation and Misfit Dislocations in Continuously- and Step-Graded InxGa1-xAs/GaAs (001) and GaAs1-yPy/GaAs (001) Metamorphic Buffer Layers

2015 ◽  
Vol 24 (03n04) ◽  
pp. 1520009 ◽  
Author(s):  
Tedi Kujofsa ◽  
John E. Ayers
Keyword(s):  
Dislocation Density ◽  
Buffer Layer ◽  
Minimum Energy ◽  
Lattice Relaxation ◽  
Structure Type ◽  
Elastic Stiffness ◽  
Buffer Layers ◽  
Threading Dislocation ◽  
Misfit Dislocations ◽  
Metamorphic Buffer

The inclusion of metamorphic buffer layers (MBL) in the design of lattice-mismatched semiconductor heterostructures is important in enhancing reliability and performance of optical and electronic devices. These metamorphic buffer layers usually employ linear grading of composition, and materials including InxGa1-xAs and GaAs1-yPy have been used. Non-uniform and continuously graded profiles are beneficial for the design of partially-relaxed buffer layers because they reduce the threading dislocation density by allowing the distribution of the misfit dislocations throughout the metamorphic buffer layer, rather than concentrating them at the interface where substrate defects and tangling can pin dislocations or otherwise reduce their mobility as in the case of uniform compositional growth. In this work we considered heterostructures involving a linearly-graded (type A) or step-graded (type B) buffer layer grown on a GaAs (001) substrate. For each structure type we present minimum energy calculations and compare the cases of cation (Group III) and anion (Group V) grading. In addition, we studied the (i) average and surface in-plane strain and (ii) average misfit dislocation density for heterostructures with various thickness and compositional profile. Moreover, we show that differences in the elastic stiffness constants give rise to significantly different behavior in these two commonly-used buffer layer systems.

Mid-10 cm−2 threading dislocation density in optimized high-Ge content relaxed graded SiGe on Si for III-V solar on Si

2004 ◽  
Vol 836 ◽  
Author(s):  
David M. Isaacson ◽  
Carl L. Dohrman ◽  
Arthur J. Pitera ◽  
Saurabh Gupta ◽  
Eugene A. Fitzgerald
Keyword(s):  
Solar Cells ◽  
Dislocation Density ◽  
Minority Carrier ◽  
Dislocation Nucleation ◽  
Threading Dislocation ◽  
High Quality ◽  
Significant Development ◽  
Threading Dislocation Density ◽  
Free Growth

ABSTRACTWe present a framework for obtaining high quality relaxed graded SiGe buffers on Si for III-V integration. By avoiding dislocation nucleation in Si1−xGex layers of x>0.96, we have achieved a relaxed Si0.04Ge0.96 platform on Si(001) offcut 2° that has a threading dislocation density of 7.4×105 cm−2. This 2° offcut orientation was determined to be the minimum necessary for APB-free growth of GaAs. Furthermore, we found that we could compositionally grade the Ge content in the high-Ge portion of the buffer at up to 17 %Ge μm−1 with no penalty to the dislocation density. The reduction in both threading dislocation density and buffer thickness exhibited by our method is an especially significant development for relatively thick minority-carrier devices which use III-V materials such as multi-junction solar cells.

Role of substrate threading dislocation density in relaxation of highly strained InGaAs/GaAs quantum well structures

1990 ◽  
Vol 56 (14) ◽  
pp. 1350-1352 ◽  
Author(s):  
J. F. Klem ◽  
W. S. Fu ◽  
P. L. Gourley ◽  
E. D. Jones ◽  
T. M. Brennan ◽  
...  
Keyword(s):  
Dislocation Density ◽  
Quantum Well ◽  
Threading Dislocation ◽  
Quantum Well Structures ◽  
Threading Dislocation Density ◽  
Highly Strained

Strategies For Direct Monolithic Integration of AlxGa(1−x)As/InxGa(1−x)As LEDS and Lasers On Ge/GeSi/Si Substrates Via Relaxed Graded GexSi(1−x) Buffer Layers

2001 ◽  
Vol 692 ◽  
Author(s):  
Michael E. Groenert ◽  
Christopher W. Leitz ◽  
Arthur J. Pitera ◽  
Vicky K. Yang ◽  
Harry Lee ◽  
...  
Keyword(s):  
Chemical Vapor ◽  
Threshold Current ◽  
Buffer Layers ◽  
Threading Dislocation ◽  
Carrier Lifetimes ◽  
Si Substrates ◽  
Dislocation Densities ◽  
Minority Carrier Lifetimes ◽  
Current Densities ◽  
High Series

AbstractAlxGa(1−x)As/GaAs quantum well lasers have been demonstrated via organometallic chemical vapor deposition (OMCVD) on relaxed graded GexSi(1−x) virtual substrates on Si. Despite unoptimized laser structures with high series resistance and large threshold current densities, surface threading dislocation densities as low as 2×106 cm−2 enabled cw room-temperature lasing at a wavelength of 858nm. The laser structures are oxide-stripe gain-guided devices with differential quantum efficiencies of 0.16 and threshold current densities of 1550A/cm2. Identical devices grown on commercial GaAs substrates showed differential quantum efficiencies of 0.14 and threshold current densities of 1700A/cm2. This comparative data agrees with our previous measurements of near-bulk minority carrier lifetimes in GaAs grown on Ge/GeSi/Si substrates. A number of GaAs/Ge/Si integration issues including thermal expansion mismatch and Ge autodoping behavior in GaAs were overcome.

scholarly journals Снижение плотности прорастающих дислокаций в темплейтах AlN/c-сапфир, выращенных методом плазменно-активированной молекулярно-пучковой эпитаксии

2020 ◽  
Vol 46 (8) ◽  
pp. 36
Author(s):  
В.В. Ратников ◽  
Д.В. Нечаев ◽  
А.В. Мясоедов ◽  
О.А. Кошелев ◽  
В.Н. Жмерик
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Flux Ratio ◽  
Buffer Layers ◽  
Stress Generation ◽  
Threading Dislocation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Regimes ◽  
Dislocation Densities

Multiple-crystal X-ray diffraction and a multi-beam optical stress sensor were used to study AlN/c-sapphire templates grown by plasma-assisted molecular beam epitaxy. The influence of the nucleation and buffer layers growth regimes, temperature, the ratio between Al and N* growth fluxes on the stress generation and the character of the dislocation structure were analyzed. Templates with the best crystal quality with screw and edge threading dislocation densities in a range of 4∙10^8 and 8∙10^9 cm-2, respectively, were obtained at the flux ratio of Al to N* close to 1 by using two-stage temperature regimes.

Engineering Dislocation Dynamics in Inx(AlyGa1−y)1−xP Graded Buffers Grown on Gap by Movpe

1998 ◽  
Vol 510 ◽  
Author(s):  
A.Y. Kim ◽  
E.A. Fitzgerald
Keyword(s):  
Surface Roughness ◽  
Dislocation Density ◽  
Growth Conditions ◽  
Dislocation Nucleation ◽  
Dislocation Dynamics ◽  
Threading Dislocation ◽  
High Quality ◽  
Movpe Growth ◽  
Threading Dislocation Density ◽  
Buffer Design

AbstractTo engineer high-quality Inx(AlyGa1−y)1−x P/Ga1−xP graded buffers, we have explored the effects of graded buffer design and MOVPE growth conditions on material quality. We demonstrate that surface roughness causes threading dislocation density (TDD) to increase with continued grading: dislocations and roughness interact in a recursive, escalating cycle to form pileups that cause increasing roughness and dislocation nucleation. Experiments show that V/III ratio, temperature, and grading rate can be used to control dislocation dynamics and surface roughness in InxGa1−xP graded buffers. Control of these parameters individually has resulted in x = 0.34 graded buffers with TDD = 5 × 106 cm−2and roughness = 15 nm and a simple optimization has resulted in TDD = 3 × 106 cm −2and roughness = 10 un. Our most recent work has focused on more sophisticated optimization and the incorporation of aluminum for x > 0.20 to keep the graded buffer completely transparent above 545 nm. Given our results, we expect to achieve transparent, device-quality Inx(AlyGa1−y)1−x P/GaP graded buffers with TDD < 106 cm−2

The Reduction of The Defect Density in CdTe Buffer Layers for The Growth of HgCdTe Infrared Photodiodes on Si (211) Substrates

1997 ◽  
Vol 484 ◽  
Author(s):  
H.-Y. Wei ◽  
L. Salamanca-Riba ◽  
N. K. Dhar
Keyword(s):  
Dislocation Density ◽  
Defect Density ◽  
Three Dimensional ◽  
Buffer Layers ◽  
Threading Dislocation ◽  
Si Substrates ◽  
Migration Enhanced Epitaxy ◽  
Threading Dislocation Density ◽  
Order Of Magnitude ◽  
Cdte Buffer

CdTe epilayers were grown by molecular beam epitaxy on As-passivated nominal (211) Si substrates using thin interfacial ZnTe layers. By using thin recrystallized (initially amorphous) ZnTe buffei layers, we utilized migration enhanced epitaxy (MEE) in the ZnTe layer and overcome the tendency toward three dimensional nucleation. The threading dislocation densities in 8–9 tm thick CdTe films deposited on the recrystallized amorphous ZnTe films were in the range of 2 to 5 × 105 cm−2. In addition to the reduction of threading dislocation density, the interface between the ZnTe layers and the Si substrate is much smoother and the microtwin density is an order of magnitude lower than in regular MEE growth. In order to understand the initial nucleation mechanism of the ZnTe on the As precursor Si surface, we also grew ZnTe epilayers on Te precursor treated Si substrates. The growth mode, microtwin density, and threading dislocation density are compared for films grown on Si substrates with different surface precursors and grown by different growth methods.

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