Planar Defects, Voids and their Relationship in 3C-SiC Layers

One of the problems with Si(001)/3C-SiC templates is that they involve highly defective interfaces due to the presence of misfit dislocations, voids and planar defects that degrade the SiC layer quality. A way to accommodate the high lattice mismatch between these materials and reduce the voids density is to carbonize the Si substrate before the epitaxial growth. In this contribution an alternative way to reduce planar defects density is presented by analyzing the relationship between planar defects and voids. Planar view and cross section transmission electron microscopy micrographs show a diminution of planar defects in the regions surrounding the voids. Due to the lower elastic energy over the voids and/or to a lateral growth in these regions, the generation of planar defects is partially deactivated, improving locally the crystalline quality of the SiC layer. The introduction of such cavities can be thus seen as a new parameter of Si/SiC templates design.

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FABRICATION AND CHARACTERIZATION OF FUNCTIONALLY GRADED Ni–Ti MULTILAYER THIN FILMS

Functional Materials Letters ◽

10.1142/s1793604709000570 ◽

2009 ◽

Vol 02 (02) ◽

pp. 61-66 ◽

Cited By ~ 10

Author(s):

H. TIAN ◽

D. SCHRYVERS ◽

K. P. MOHANCHANDRA ◽

G. P. CARMAN ◽

J. VAN HUMBEECK

Keyword(s):

Cross Section ◽

Functionally Graded ◽

Multilayer Thin Films ◽

Si Substrate ◽

Transmission Electron Microscopy Micrographs ◽

Transmission Electron ◽

Alloy Target ◽

Fabrication And Characterization ◽

Better Than

A functionally graded multilayer Ni – Ti thin film was deposited on a SiO 2/ Si substrate by d.c. sputtering using a ramped heated Ni – Ti alloy target. The stand-alone films were crystallized at 500°C in vacuum better than 10-7 Torr. Transmission electron microscopy micrographs taken along the film cross section show two distinct regions, thin and thick, with weak R and B2 phases, respectively. The film compositions along the thickness were measured and quantified using the standard-less EELSMODEL method. The film deposited during the initial thermal ramp (thin regions) displays an average of 54 at.% Ni while the film deposited at a more elevated target temperature (thick regions) shows about 51 at.% Ni .

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Transmission Electron Microscopy studies of the vacancy ordering in YSI2-X thin films

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100087124 ◽

1991 ◽

Vol 49 ◽

pp. 562-563

Author(s):

F.-R. Chen ◽

T. L. Lee ◽

L. J. Chen

Keyword(s):

Crystal Structure ◽

Electron Microscopy ◽

Thin Films ◽

Diffraction Pattern ◽

Annealing Temperature ◽

Lattice Mismatch ◽

Si Substrate ◽

Metal Thin Films ◽

Transmission Electron ◽

Vacancy Ordering

YSi2-x thin films were grown by depositing the yttrium metal thin films on (111)Si substrate followed by a rapid thermal annealing (RTA) at 450 to 1100°C. The x value of the YSi2-x films ranges from 0 to 0.3. The (0001) plane of the YSi2-x films have an ideal zero lattice mismatch relative to (111)Si surface lattice. The YSi2 has the hexagonal AlB2 crystal structure. The orientation relationship with Si was determined from the diffraction pattern shown in figure 1(a) to be and . The diffraction pattern in figure 1(a) was taken from a specimen annealed at 500°C for 15 second. As the annealing temperature was increased to 600°C, superlattice diffraction spots appear at position as seen in figure 1(b) which may be due to vacancy ordering in the YSi2-x films. The ordered vacancies in YSi2-x form a mesh in Si plane suggested by a LEED experiment.

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

Materials Science Forum ◽

10.4028/www.scientific.net/msf.527-529.1513 ◽

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.

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

MRS Proceedings ◽

10.1557/proc-0891-ee10-01 ◽

2005 ◽

Vol 891 ◽

Cited By ~ 1

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.

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Equilibrium Analysis of Lattice-Mismatched Nanowire Heterostructures

MRS Proceedings ◽

10.1557/proc-737-f10.4 ◽

2002 ◽

Vol 737 ◽

Cited By ~ 5

Author(s):

E. Ertekin ◽

P.A. Greaney ◽

T. D. Sands ◽

D. C. Chrzan

Keyword(s):

Simple Model ◽

Misfit Dislocation ◽

Critical Thickness ◽

Lattice Mismatch ◽

Equilibrium Analysis ◽

Misfit Dislocations ◽

Model Based ◽

Large Lattice ◽

Large Lattice Mismatch

ABSTRACTThe quality of lattice-mismatched semiconductor heterojunctions is often limited by the presence of misfit dislocations. Nanowire geometries offer the promise of creating highly mismatched, yet dislocation free heterojunctions. A simple model, based upon the critical thickness model of Matthews and Blakeslee for misfit dislocation formation in planar heterostructures, illustrates that there exists a critical nanowire radius for which a coherent heterostructured nanowire system is unstable with respect to the formation of misfit dislocations. The model indicates that within the nanowire geometry, it should be possible to create perfect heterojunctions with large lattice-mismatch.

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The Effects of Nucleation and Growth on Epitaxy in the CoSi2/Si System

MRS Proceedings ◽

10.1557/proc-10-101 ◽

1981 ◽

Vol 10 ◽

Cited By ~ 1

Author(s):

J. M. Gibson ◽

J. C. Bean ◽

J. M. Poate ◽

R. T. Tung

Keyword(s):

Cross Section ◽

Defect Structure ◽

Ultrahigh Vacuum ◽

Nucleation And Growth ◽

Silicon Substrates ◽

Pinning Mechanism ◽

Preparation Conditions ◽

Transmission Electron ◽

Silicide Growth

The epitaxial perfection and microstructure in thin CoSi2 (111) (and NiSi2) films on silicon has been examined using transmission electron microscopy, including high resolution cross section techniques. We find that, under ultrahigh vacuum preparation conditions only, genuine single-crystal epitaxy can occur for bothreacted and codeposited CoSi2 films. A unique interfacial defect structure is associated with this epitaxy, in which the silicide films are rotated through 180° about (111) with respect to the silicon substrates. Under less than perfectly clean conditions epitaxial perfection is never obtained for CoSi2. Moreover such perfection has never been attained under any conditions for NiSi2 on Si(111). By studying the evolution of epitaxy and defect structure in thin and thick films we have proposed a model to explain the unique quality of ultrahigh vacuum CoSi2 films. The model invokes a defect pinning mechanism to explain the dominance of the 180°-rotated epitaxy during silicide growth.

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

MRS Proceedings ◽

10.1557/proc-500-63 ◽

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.

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Defect Generation And Evolution In The Hydrothermal Growth Of Epitaxial BaTiO3 Thin Films

MRS Proceedings ◽

10.1557/proc-474-55 ◽

1997 ◽

Vol 474 ◽

Author(s):

L. Zhao ◽

A. T. Chien ◽

F. F. Lange ◽

J. S. Speck

Keyword(s):

Thin Films ◽

Cross Section ◽

Interfacial Layer ◽

Dislocation Network ◽

Misfit Dislocations ◽

Plan View ◽

Transmission Electron ◽

Defects Analysis ◽

Film Substrate ◽

Growth Evolution

ABSTRACTThe structure of epitaxial BaTiO3 thin films prepared by hydrothermal synthesis on (001) SrTiO3 substrates was studied by transmission electron microscopy (TEM). The growth evolution was followed from initial island formation, through island impingement and fusion. Plan view and cross-section imaging demonstrated that the films grew by an unusual islanding mechanism. Electron diffraction showed the islands and the fully formed film are single crystal with mosaic character and in all cases strain relaxed. Cross-section TEM of the early growth films showed a several monolayer thick interfacial layer and the film/substrate region had no misfit dislocations. In the fully formed films, this interfacial layer was not observed, however a clear misfit dislocation network was observed. Defects analysis shows that the misfit dislocations have pure edge character with <100> Une directions, and <010> Burgers vectors (parallel to the film/substrate interface).

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

MRS Proceedings ◽

10.1557/proc-401-109 ◽

1995 ◽

Vol 401 ◽

Cited By ~ 11

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.

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TEM Study of Defects in Laterally Overgrown GaN Layers

MRS Internet Journal of Nitride Semiconductor Research ◽

10.1557/s1092578300002891 ◽

1999 ◽

Vol 4 (S1) ◽

pp. 459-464 ◽

Cited By ~ 11

Author(s):

Z. Liliental-Weber ◽

M. Benamara ◽

W. Swider ◽

J. Washburn ◽

J. Park ◽

...

Keyword(s):

Electron Microscopy ◽

Point Defects ◽

Crystallographic Direction ◽

Initial Growth ◽

Lateral Growth ◽

Planar Defects ◽

Transmission Electron ◽

Defects And Impurities ◽

Two Sides ◽

Line Direction

Transmission electron microscopy was applied to study defects in laterally overgrown GaN layers, with initial growth on Al2O3 substrates followed by further growth over SiO2 masks. Dislocations found in the overgrown areas show changes in line direction. Most dislocations propagate along c-planes. In the overgrown material planar defects (faulted loops) are present on c-planes and their presence is most probably related to segregation of excess point defects and impurities present in this material. They appear to be initiated by the fast lateral growth. Some dislocations with screw orientation become helical resulting from climb motion.Formation of voids and also a high dislocation density was observed at the boundaries where two overgrowing fronts meet. Tilt and twist components were observed for these boundaries that were different for different overgrown strips grown in the same crystallographic direction suggesting that the GaN subgrain orientations on the two sides of a SiO2 mask are responsible for the final tilt and twist value.

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