Modeling Misfit Dislocation Arrays for the Growth of Low-Defect Density AlSb on Si

2006 ◽  
Vol 934 ◽  
Author(s):  
Anitha Jallipalli ◽  
G. Balakrishnan ◽  
S.H. Huang ◽  
A. Khoshakhlagh ◽  
L.R. Dawson ◽  
...  
Keyword(s):  
Lattice Mismatch ◽  
Defect Density ◽  
Analytical Models ◽  
Misfit Dislocations ◽  
Growth Interface ◽  
Strain Relief ◽  
Transmission Electron ◽  
Dislocation Arrays ◽  
Two Systems ◽  
Extensive Growth

ABSTRACTWe present analytical models and experimental results to describe low-defect density growth (∼ 6 × 105/cm2) of highly mismatched antimonides on Si and GaAs substrates, with strain relief achieved at the growth interface through periodic, 90° interfacial misfit dislocations (IMF). We use molecular mechanics (MM) based modeling techniques to understand, at the atomic level, the spontaneous formation and energetics of these IMF. We have modeled, grown and characterized two systems extensively, these are - AlSb on Si with ∼ 13% mismatch and GaSb on GaAs with 7.83% lattice mismatch. Growth of these materials by molecular beam epitaxy (MBE) and subsequent High-Resolution Transmission Electron Microscopy (HR-TEM) has indicated that there is no tetragonal distortion in these two systems despite the high lattice mismatch. Instead, the mismatched epi-layers spontaneously form periodic IMF arrays that run along both [110] and [1-10] directions and relieve almost 100% of the strain in a few monolayers of deposition. To model this form of strain relief, we use existing theories of strain relief adapted for very high strain conditions and we also use bond energetics to model the strain-relieving interface. The IMFs in these systems are periodic and so is the deviation in bond lengths and bond angles, which restricts our calculation space to a finite number of elements. We shall also demonstrate extensive growth and characterization results of the materials grown with a particular emphasis on the strain-relieving interface to show excellent agreement of the experimental data with the proposed models. The high quality and low-defect density in AlSb grown on Si, has helped us demonstrate optically pumped IR VCSELs and edge emitters monolithically on Si (001) and this data will also be presented.

Growth of a-plane ZnO Thin Films on r-plane Sapphire by Plasma-assisted MBE

2005 ◽  
Vol 891 ◽  
Author(s):  
Junqing Q. Xie ◽  
J. W. Dong ◽  
A. Osinsky ◽  
P. P. Chow ◽  
Y. W. Heo ◽  
...  
Keyword(s):  
Thin Films ◽  
Lattice Mismatch ◽  
Defect Density ◽  
Zno Thin Films ◽  
Rf Plasma ◽  
Misfit Dislocations ◽  
Epitaxial Relationship ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Small Lattice

ABSTRACTZnO thin films have been epitaxially grown on r-plane sapphire by RF-plasma-assisted molecular beam epitaxy. X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies indicate that the epitaxial relationship between ZnO and r-plane sapphire is (1120)ZnO // (1102)sapphire and [0001]ZnO // [1101]sapphire. Atomic force microscopy measurements reveal islands extended along the sapphire [1101] direction. XRD omega rocking curves for the ZnO (1120) reflection measured either parallel or perpendicular to the island direction suggest the defect density anisotropy along these directions. Due to the small lattice mismatch along the ZnO [0001] direction, few misfit dislocations were observed at the ZnO/Al2O3 interface in the high-resolution cross-sectional TEM image with the zone axis along the ZnO [1100] direction.

Strain Relaxation in GaN/AlN Films Grown on Vicinal and On-Axis SiC Substrates

2006 ◽  
Vol 527-529 ◽  
pp. 1513-1516
Author(s):  
J. Bai ◽  
X. Huang ◽  
Balaji Raghothamachar ◽  
Michael Dudley ◽  
B. Wagner ◽  
...  
Keyword(s):  
High Resolution ◽  
Lattice Mismatch ◽  
Strain Relaxation ◽  
Crystalline Quality ◽  
Misfit Dislocations ◽  
Vicinal Surface ◽  
Burgers Vector ◽  
Surface Steps ◽  
Transmission Electron ◽  
Initial Stage

Strain relaxation in the GaN/AlN/6H-SiC epitaxial system grown by vicinal surface epitaxy (VSE) is investigated and compared with that in on-axis epitaxy. High resolution x-ray diffraction (HRXRD) measurements show that GaN films grown by VSE have improved crystalline quality. High resolution transmission electron microscope (HRTEM) studies reveal that there are two types of misfit dislocations (MDs) at AlN/6H-SiC interfaces: 60˚ complete dislocations along <1120 > directions with Burgers vector 1/3<1120 > and 60˚ Shockley partials along <10 10 > directions with Burgers vector 1/3<10 10 >. The latter are usually geometrical partial misfit dislocations (GPMDs) that are dominant in VSE to accommodate the lattice mismatch and stacking sequence mismatch simultaneously. In VSE, it is the high-density GPMDs formed at the vicinal surface steps that facilitate rapid strain relaxation at the initial stage of deposition and hence lead to superior crystalline quality of the subsequently grown GaN films.

Microstructural and Electrical Characterization of Misfit Dislocations at the InAs/GaP Heterointerface

1997 ◽  
Vol 500 ◽  
Author(s):  
V. Gopal ◽  
T. P. Chin ◽  
A. L. Vasiliev ◽  
J. M. Woodall ◽  
E. P. Kvam
Keyword(s):  
Misfit Dislocation ◽  
Lattice Mismatch ◽  
Electrical Characterization ◽  
Growth Conditions ◽  
Misfit Dislocations ◽  
Ir Detectors ◽  
Mbe Growth ◽  
Transmission Electron ◽  
Hall Effect Measurements ◽  
Edge Dislocations

ABSTRACTInAs is a narrow band gap semiconductor with potential for such applications as IR detectors, low temperature transistors, etc‥ However, the lack of suitable substrates has hampered progress in the development of InAs based devices. In the present study, InAs was grown by Molecular Beam Epitaxy on (001) GaP substrates. Though this system has a high lattice mismatch, (∼11%), certain MBE growth conditions result in 80% relaxed InAs layers on GaP with the mismatch accommodated predominantly by 90° pure edge dislocations. Misfit dislocation microstructures were studied using Transmission Electron Microscopy. Electrical characterization using lateral conductance and Hall effect measurements were also performed. Preliminary results indicate the possibility of misfit dislocation related conductivity. The possible correlation between interface structure and electrical properties is discussed.

Structural Defects and Critical Electric Field in 3C-SiC

2006 ◽  
Vol 527-529 ◽  
pp. 431-434 ◽  
Author(s):  
Michael A. Capano ◽  
A.R. Smith ◽  
Byeung C. Kim ◽  
E.P. Kvam ◽  
S. Tsoi ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Electric Field ◽  
Lattice Mismatch ◽  
Defect Density ◽  
Chemical Vapor ◽  
Structural Defects ◽  
X Ray ◽  
Transmission Electron ◽  
Current Voltage ◽  
P Type

3C-SiC p-type epilayers were grown to thicknesses of 1.5, 3, 6 and 10 μm on 2.5° off-axis Si(001) substrates by chemical vapor deposition (CVD). Silane and propane were used as precursors. Structural analysis of epilayers was performed using transmission electron microscopy (TEM), high-resolution x-ray diffractometry (HRXRD), and Raman spectroscopy. TEM showed defect densities (stacking faults, twins and dislocations) decreasing with increasing distance from the SiC/Si interface as the lattice mismatch stress is relaxed. This observation was corroborated by a monotonic decrease in HRXRD peak width (FWHM) from 780 arcsecs (1.5 μm thick epilayer) to 350 arcsecs (10 μm thick epilayer). Significant further reduction in x-ray FWHM is possible because the minimum FWHM detected is greater than the theoretical FWHM for SiC (about 12 arcsecs). Raman spectroscopy also indicates that the residual biaxial in-plane strain decreases with increasing epilayer thickness initially, but becomes essentially constant between 6 and 10 μm. Structural defect density shows the most significant reduction in the first 2 μm of growth. Phosphorus implantation was used to generate n+/p junctions for the measurement of the critical electric field in 3C-SiC. Based on current-voltage analyses, the critical electric field in p-type 3C-SiC with a doping of 2x1017 cm-3 is 1.3x106 V/cm.

Epitaxial Growth and Structure of Cubic and Pseudocubic Perovskite Films on Perovskite Substrates

1995 ◽  
Vol 401 ◽  
Author(s):  
P. A. Langjahr ◽  
T. Wagner ◽  
M. RÜhle ◽  
F. F. Lange
Keyword(s):  
Electron Microscopy ◽  
Epitaxial Growth ◽  
Lattice Mismatch ◽  
High Resolution Electron Microscopy ◽  
Lattice Parameter ◽  
Ternary Oxide ◽  
Misfit Dislocations ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Resolution Electron

AbstractCubic and pseudocubic perovskite films on perovskite substrates are used to study the influence of the lattice mismatch on the epitaxial growth of thin films on substrates of the same structure. For the growth of the films, a metalorganic decomposition route (MOD) using 2-ethylhexanoates and neodecanoates as precursors, was developed. The decomposition of the precursors was investigated with thermogravimetric analysis (TGA) and x-ray diffraction (XRD). The films were spin-coated on (001)-oriented SrTiO3- and LaAlO3-substrates, pyrolyzed and afterwards annealed between 600°C and 1200°C. XRD-nvestigations and conventional transmission electron microscopy (CTEM) show, that epitaxial films with the orientation relationship [100](001) film ║ [100](001) substrate can be grown. With XRD, it could be shown, that not only ternary oxide films (SrZrO3, BaZrO3 and BaCeO3), but also perovskite solid solution films (SrTi0.5Zr0.5O3and BaCe0.5Zr0.5O3) can be prepared. Strong interdiffusion, detected by a shift of the film lattice parameter towards the substrate lattice parameter was found in SrZrO3- and BaZrO3-films on SrTiO3, annealed at temperatures above 1050°C. High resolution electron microscopy (HREM) studies of SrZrO3 on SrTiO3 show that a crystalline semicoherent interface with a periodical array of misfit dislocations is present.

Dissociation of Misfit Dislocations in GeSi/{111}Si Interfaces

1993 ◽  
Vol 319 ◽  
Author(s):  
Frank Ernst
Keyword(s):  
Lattice Mismatch ◽  
Stacking Faults ◽  
Chemical Vapor ◽  
Interfacial Area ◽  
Dark Field ◽  
Dislocation Network ◽  
Misfit Dislocations ◽  
Si Substrates ◽  
Weak Beam ◽  
Transmission Electron

AbstractThe accommodation of lattice mismatch is studied in Ge0.15Si0.85 layers grown epitaxially on {111}-oriented Si substrates by chemical vapor deposition (CVD) at 1100°C. Weak beam dark field microscopy reveals a regular misfit dislocation network, which resembles the honeycomb network of edge-type dislocations anticipated by the O-lattice theory. In contrast to the latter, however, the real network exhibits extended nodes where the misfit dislocations dissociate into misfit partial dislocations. Between the partials, high resolution transmission electron microscopy (HRTEM) reveals intrinsic and extrinsic stacking faults. Owing to the presence of these stacking faults, three different atomistic structures of the GeSi/Si interface coexist and compete for the interfacial area according to their energy. The observed configuration is shown to minimize the total energy of the interface.

The Nucleation and Propagation of Misfit Dislocations aear the Critical Thickness in Ge-Si Strained Epilayers

1987 ◽  
Vol 104 ◽  
Author(s):  
E. P. Kvam ◽  
D. J. Eaglesham ◽  
D. M. Maher ◽  
C. J. Humphreys ◽  
J. C. Bean ◽  
...  
Keyword(s):  
Lattice Parameter ◽  
Dislocation Segment ◽  
Misfit Dislocations ◽  
X Ray Diffraction ◽  
Parameter Mismatch ◽  
Growth Interface ◽  
Edge Type ◽  
X Ray ◽  
Transmission Electron ◽  
Dislocation Behavior

ABSTRACTThe nucleation and propagation of misfit dislocations in Ge-Si strained epilayers on (100) Si have been investigated using transmission electron microscopy and X-ray diffraction topography at low lattice parameter mismatch (˜ 0.8%). Misfit dislocations nucleate as half loops which are predominantly unfaulted (> 90%) at the advancing growth interface. Under the driving force of the epilayer strain, unfaulted half loops glide and expand on inclined { 111 }planes toward the heterointerface (i.e. substrate/epilayer interface). These unfaulted half loops consist of a 60°-dislocation segment which lies along < 011> in a plane parallel to the heterointerface (i.e. (100)) and this segment is connected to the growth interface by two screw dislocation segments which both lie on the same inclined {111} glide plane. As 60° dislocations reach the heterointerface on each of the four inclined {111} variants, they form an orthogonal array of misfit dislocations which lie along [011] and [011]. At higher lattice parameter mismatch (˜ 2%), there appear to be some important changes in the dislocation behavior and these changes result in orthogonal arrays of heterointerface dislocations which are predominantly edge type (i.e. 90°dislocations).

Surface Morphology of SiGe Epitaxial Layers Grown on Uniquely Oriented Si Substrates

2000 ◽  
Vol 648 ◽  
Author(s):  
Morgan E. Ware ◽  
Robert J. Nemanich
Keyword(s):  
Surface Morphology ◽  
Lattice Mismatch ◽  
Morphological Structure ◽  
Epitaxial Layers ◽  
Misfit Dislocations ◽  
Force Microscopy ◽  
Si Substrates ◽  
Atomic Force ◽  
Transmission Electron ◽  
Relationship Of

AbstractThe 4% lattice mismatch between Si and Ge creates strain in epitaxial layers of SiGe alloys on Si, and this strain can manifest itself in the morphological structure of the surface of the epitaxial layer. This study explores the relationship of the evolution of the surface morphology of SiGe layers grown on a range of Si surface orientations. We have grown thin, strained and thick, relaxed layers of Si0.7Ge0.3 by solid source molecular beam epitaxy on substrates with surface normals rotated from [001] towards [111] by angles of θ = (0, 2, 4, 10, 22) degrees. The surface morphology was investigated by atomic force microscopy, which showed considerable ordering of surface features on relaxed samples. These features evolve from hut-like structures at 0 degrees to large mesa-like structures separated by pits and crevices at 22 degrees. The organization of these features is also shown to vary with the substrate orientation. Each surface has characteristic directions along which features are aligned, and these directions vary continuously with the angle of rotation of the substrate. Transmission electron microscopy confirmed that misfit dislocations had formed along those same directions. The state of relaxation of each layer is quantified by Raman spectroscopy in order to make a direct correlation between residual strain and surface morphology.

Characterization of Chemically Vapor Deposited GaN on Sic on a Simox Substrate

1997 ◽  
Vol 3 (S2) ◽  
pp. 487-488
Author(s):  
W.L. Zhou ◽  
P. Pirouz
Keyword(s):  
Lattice Mismatch ◽  
Defect Density ◽  
Silicon Layer ◽  
Large Defect ◽  
Cross Sectional ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Transmission Electron ◽  
Potential Applications ◽  
Gan Film

GaN has been intensively studied because of its potential applications for the fabrication of blue- or ultraviolet-light emitting devices. Sapphire (α-Al2O3) is generally used as the substrate for growth of GaN film. However, the large lattice mismatch between GaN and Al2O3is a possible cause of the large defect density in the GaN films. Consequently, alternative substrates are being studied with the aim of growing films of lesser defect densities and improved opto-electronic properties. In this paper, we report a transmission electron microscopy (TEM) study of a GaN film grown on cubic SiC which has been obtained by carbonization of the top silicon layer of a SIMOX substrate, i.e. the system GaN/SiC/Si/SiO2/Si.Cross-sectional TEM specimens were prepared by the conventional sandwich technique with the foil surface normal to the Si[l10] direction. The composite sample was ground and dimpled to a thickness of ∼ 10μm, and subsequently ion thinned to electron transparency.

1.6 μm Emission from InAs Quantum Dots grown on a GaAs Substrate using an AlGaAsSb Metamorphic Buffer

2002 ◽  
Vol 737 ◽  
Author(s):  
G. Balakrishnan ◽  
S. Birudavolu ◽  
L. R. Dawson ◽  
D. L. Huffaker ◽  
Huifang Xu ◽  
...  
Keyword(s):  
Gaas Substrate ◽  
Lattice Mismatch ◽  
Defect Density ◽  
Matrix Material ◽  
Metamorphic Buffer ◽  
Transmission Electron ◽  
Digital Alloy ◽  
The Matrix ◽  
Matrix Lattice ◽  
Wavelength Emission

ABSTRACTWe report 1.6 μm emission from InAs QDs (QDs) grown on a GaAs substrate. The ensemble is grown on a graded digital alloy (DA), which increases the matrix lattice constant from 5.65 Å to 5.77 Å. The reduced lattice mismatch between the InAs and matrix material produces larger QDs and thereby allows longer wavelength emission compared to standard growth techniques. The resulting QD density ranges from 2×1010 to 8×1010/cm2 with QD dimensions of 5nm x 30nm measured using atomic force microscopy (AFM). According to x-ray diffraction (XRD) data and transmission electron microscopy (TEM), the metamorphic buffer is unstrained with low defect density.

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