Stress-driven surface evolution in heteroepitaxial thin films: Anisotropy of the two-dimensional roughening mode

1999 ◽  
Vol 14 (8) ◽  
pp. 3247-3256 ◽  
Author(s):  
Cengiz S. Ozkan ◽  
William D. Nix ◽  
Huajian Gao
Keyword(s):  
Defect Formation ◽  
Ex Situ ◽  
Surface Roughening ◽  
Misfit Dislocations ◽  
Two Dimensional ◽  
Anisotropic Behavior ◽  
Surface Evolution ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron

We have analyzed the anisotropic behavior of surface roughening in Si1−xGex/Si(001) heterostructures by use of methods of elastic analysis of undulated surfaces and perturbation analysis on the basis of global energy variations associated with surface evolution. Both methods have shown that the two-dimensional stage of surface roughening preferentially takes place in the form of ridges aligned along the two orthogonal 〈100〉 type directions. This prediction has been confirmed by ex situ experimental observations of surface evolution by use of atomic force microscopy and transmission electron microscopy in both subcritically and supercritically thick Si1−xGex films grown on Si(001) substrates. Further experiments in supercritically thick films have revealed a remarkable interplay between defect formation and surface evolution: the formation of a network of 〈110〉?misfit dislocations in the latter stages alters the evolution process by rotating the ridge formations toward the 〈110〉 type directions.

STRUCTURAL AND MAGNETIC PROPERTIES OF EPITAXIAL Ni80Fe20 THIN FILMS ON Cu/Si

1995 ◽  
Vol 02 (04) ◽  
pp. 427-437 ◽  
Author(s):  
I. HASHIM ◽  
H.S. JOO ◽  
H.A. ATWATER
Keyword(s):  
Magnetic Properties ◽  
Domain Walls ◽  
High Energy ◽  
Ex Situ ◽  
Misfit Dislocations ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Crystal Films

Single-crystal films of permalloy ( Ni 80 Fe 20) were grown on Cu (001) seed layers oriented epitaxially with Si (001). The microstructural properties were measured using in-situ reflection high-energy electron diffraction, and ex-situ transmission electron microscopy, x-ray diffraction, and atomic force microscopy, whereas the magnetic properties were probed using in-situ magneto-optic Kerr effect and ex-situ vibrating sample magnetometry. Anisotropic magnetoresistance and resistivity for some of the samples were also measured. The coercivity for thinner (≤5 nm) Ni 80 Fe 20 was significantly higher (10–20 Oersteds) than polycrystalline films deposited on SiO 2/ Si , and was also higher than films deposited on lattice-matched Cu x Ni 1–x alloys. These magnetic properties were explained using a theoretical model involving interaction of domain walls with defects such as misfit dislocations and coherent islands, due to the mismatch between Ni 80 Fe 20 and Cu .

(G03 Best Paper Award Winner) Analysis of Sn Behavior During Ni/GeSn Solid-State Reaction by Correlated X-ray Diffraction, Atomic Force Microscopy, and Ex-situ/In-situ Transmission Electron Microscopy

2020 ◽  
Vol MA2020-02 (24) ◽  
pp. 1750-1750
Author(s):  
Andrea Quintero Colmenares ◽  
Patrice Gergaud ◽  
Jean-Michel Hartmann ◽  
Vincent Delaye ◽  
Nicolas Bernier ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Ex Situ ◽  
Paper Award ◽  
X Ray Diffraction ◽  
Award Winner ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron

Anisotropic Behaviour of Surface Roughening in Lattice Mismatched Heteroepitaxial Thin Films

1996 ◽  
Vol 436 ◽  
Author(s):  
Cengiz S. Ozkan ◽  
William D. Nix ◽  
Huajian Gao
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Lattice Mismatch ◽  
Surface Roughening ◽  
Silicon Substrates ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Annealing Experiments

AbstractHeteroepitaxial Si1-xGex. thin films deposited on silicon substrates exhibit surface roughening via surface diffusion under the effect of a compressive stress which is caused by a lattice mismatch. In these films, surface roughening can take place in the form of ridges which can be aligned along <100> or <110> directions, depending on the film thickness. In this paper, we investigate this anisotropic dependence of surface roughening and present an analysis of it. We have studied the surface roughening behaviour of 18% Ge and 22% Ge thin films subjected to controlled annealing experiments. Transmission electron microscopy and atomic force microscopy have been used to study the morphology and microstructure of the surface ridges and the dislocations that form during annealing.

Fabrication of Two-Dimensional PEDOT:PSS Nanosheets Through In Situ Formed Complexes

NANO ◽  
2015 ◽  
Vol 10 (01) ◽  
pp. 1550011 ◽  
Author(s):  
Kun Zhang ◽  
Shiren Wang
Keyword(s):  
In Situ Polymerization ◽  
Molecular Complexes ◽  
Water Soluble ◽  
Strong Interactions ◽  
Two Dimensional ◽  
Force Microscopy ◽  
Atomic Force ◽  
Ftir Characterization ◽  
Transmission Electron

This paper presents a simple and effective method to fabricate water-soluble two-dimensional (2D) conductive poly(3,4-ethylenedioxythiophene):poly (sodium 4-styrenesulfonate) (PEDOT:PSS) nanosheets. Linear PSS is water-soluble and exhibits a quasi 1D structure in the dilute solution. Addition of 3,4-ethylenedioxythiophene (EDOT) monomers into acidic solutions would form 2D molecular complexes due to charge attraction. In situ polymerization of the ethylenedioxythiophene monomers produces 2D poly EDOT nanosheets. Both transmission electron microscopy and atomic force microscopy characterizations have confirmed the 2D polymeric nanosheets. Further Fourier transform infrared (FTIR) characterization also validated that the 2D nanosheet is composed of EDOT-based units and Raman spectroscopy indicated the strong interactions between ethylenedioxythiophene units in the 2D nanostructures. The electrical conductivity is measured to as high as 551.58 S/m for the thin film of as-produced 2D PEDOT:PSS nanosheets.

EFFECT OF SUBSTRATE TEMPERATURE ON THE STRUCTURAL AND THE OPTICAL PROPERTIES OF CdTe (100) EPITAXIAL FILMS GROWN ON GaAs (100) SUBSTRATES

2007 ◽  
Vol 14 (04) ◽  
pp. 755-759 ◽  
Author(s):  
D. U. LEE ◽  
J. H. JUNG ◽  
T. W. KIM ◽  
H. S. LEE ◽  
H. L. PARK ◽  
...  
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Substrate Temperature ◽  
Misfit Dislocations ◽  
X Ray Diffraction ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Cdte Thin Films ◽  
Xrd Patterns

CdTe thin films were grown on GaAs (100) substrates by using molecular beam epitaxy at various temperatures. The results of the X-ray diffraction (XRD) patterns showed that the orientation of the grown CdTe thin films was the (100) orientation. XRD patterns, atomic force microscopy images, high-resolution transmission electron microscopy (HRTEM) images, and photoluminescence spectra showed that the crystallinity of CdTe (100) epilayers grown on GaAs (100) substrates was improved by increasing the substrate temperature. HRTEM images showed that misfit dislocations existed at the CdTe / GaAs heterointerface. These results can help improve understanding of the substrate temperature effect on the structural and the optical properties of CdTe (100)/ GaAs (100) heterostructures.

Si1-xGex Critical Thickness for Surface Wave Generation During UHV-CVD Growth at 525°C

1995 ◽  
Vol 399 ◽  
Author(s):  
H. Lafontaine ◽  
D.C. Houghton ◽  
B. Bahierathan ◽  
D.D. Perovic ◽  
J.-M. Baribeau
Keyword(s):  
Electron Microscopy ◽  
Surface Waves ◽  
Critical Thickness ◽  
Critical Value ◽  
Misfit Dislocations ◽  
Cross Sectional ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Cvd Growth

ABSTRACTSeveral Si1-xGex/Si heterostructures were grown at 525°C using a commercially available UHV-CVD reactor. Layers with a germanium fraction ranging from 0.15 to 0.5 were examined by means of cross-sectional transmission electron microscopy and atomic force microscopy. Surface waves were found in layers with a thickness above a critical value which decreases rapidly as the Ge fraction is increased. Both experimental and modeling results show that surface waves are generated before misfit dislocations for Ge fractions above 0.3.

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.

2D Assembly of Palladium Nanoparticles and AFM Characterization

2014 ◽  
Vol 887-888 ◽  
pp. 161-166
Author(s):  
Xiao Jun Liu ◽  
Li Yun Song ◽  
Zong Cheng Zhan ◽  
Hong He ◽  
Xue Hong Zi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Silicon Wafer ◽  
Palladium Nanoparticles ◽  
Cetyltrimethylammonium Bromide ◽  
Dip Coating ◽  
Two Dimensional ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron

The two-dimensional (2D) assembly of the palladium nanoparticles (Pd NPs) was studied in this work. The cubic Pd NPs were successfully synthesized and assembled on mica and silicon wafer in the dip-coating way. The morphology of the Pd NPs and the topography of the Pd NPs assembly on the substrates were characterized with transmission electron microscopy (TEM) and atomic force microscopy (AFM). In the process of the fabrication, the excess cetyltrimethylammonium bromide (CTAB) was removed with the deposition-redispersion strategy, the UV-vis spectra and zeta-potential of the Pd NPs colloid were measured. It was found that the assembly and AFM characterization of the Pd NPs were affected negatively by the presence of excess CTAB. The hydrophilic property of the substrate is the crucial factor to control the 2D assembly of the Pd NPs. Compared with the washed silicon wafer, mica is ultra-hydrophilic and can attract more Pd NPs.

Sign in / Sign up

Export Citation Format

Share Document