Microstructure of TiO2 rutile thin films deposited on (110) α−Al2O3

1991 ◽  
Vol 6 (11) ◽  
pp. 2417-2426 ◽  
Author(s):  
Y. Gao ◽  
K.L. Merkle ◽  
H.L.M. Chang ◽  
T.J. Zhang ◽  
D.J. Lam
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Grain Boundaries ◽  
Film Growth ◽  
Lattice Mismatch ◽  
High Resolution Electron Microscopy ◽  
Growth Direction ◽  
Orientation Relationships ◽  
Atomic Structures ◽  
Α Al2o3

TiO2 rutile thin films grown on (110) sapphire (α−Al2O3) by the MOCVD technique have been characterized by transmission electron microscopy (TEM) and high resolution electron microscopy (HREM). The TiO2 rutile thin films grew on the sapphire with two epitaxial orientations. The epitaxial orientation relationships between the rutile films (R) and the sapphire substrate (S) were found to be (1) (101)[010]R ‖ (110)[0001]s. Detailed atomic structures of near-interface regions have been investigated by HREM, providing a clear picture of the initial stage of film growth. HREM images show that about 70% of the nuclei at the interface are the (101) rutile, but most of them are very small, about 5 nm (or 2% of the film thickness) in the growth direction. The film growth was dominated by the (200) orientation. Nucleation and growth of the films will be discussed in terms of the lattice mismatch at the interface and growth rates along the two orientations. Planar defects such as twin boundaries and special grain boundaries are commonly observed in the films, especially in regions close to the substrate. The twin plane and twinning direction are {101} and 〈101〉, respectively. Special grain boundaries are found to be correlated with nucleation and twinning.

Electron Microscopy Study Of Mocvd-Grown Tio2Thin Films and Tio2/Al203 Interfaces

1990 ◽  
Vol 209 ◽  
Author(s):  
Y. Gao ◽  
K. L. Merkle ◽  
H. L. M. Chang ◽  
T. J. Zhang ◽  
D. J. Lam
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Lattice Mismatch ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Rutile Structure ◽  
Atomic Structures ◽  
Transmission Electron ◽  
Twinning Direction ◽  
Mocvd Technique

ABSTRACTTiO2 thin films grown on (1120) sapphire at 800°C by the MOCVD technique have been characterized by transmission electron microscopy. The TiO2 thin films are single crystalline and have the rutile structure. The epitaxial orientation relationship between the TiO2 thin films (R) and the substrate (S) has been foundto be: (101)[010]R║(1l20)[0001]s. Growth twins in the films are commonly observed with the twin plane{101} and twinning direction <011>. Detailed atomic structures of the twin boundaries and TiO2/α-Al203 interfaces have been investigated by highresolution electron microscopy (HREM).When the interfaces are viewed in the direction of [010]R/[000l]S, the interfaces are found to be structurally coherent in the direction of [1Ol]R/[1100]s,in which the lattice mismatch at the interfaces is about 0.5%.

Hrtem of the Cu/Mno Interface in an Internally Oxidized Cumn Alloy

1990 ◽  
Vol 183 ◽  
Author(s):  
F. Ernst
Keyword(s):  
Electron Microscopy ◽  
Lattice Mismatch ◽  
Particle Morphology ◽  
High Resolution Electron Microscopy ◽  
Orientation Relationships ◽  
Coherent Interface ◽  
Resolution Electron ◽  
Characteristic Particle ◽  
Interface Structures ◽  
The Relationship

AbstractThe structure of the Cu/MnO interface has been studied using high resolution electron microscopy (HRTEM). Interfaces were formed by internal oxidation of a CuMn alloy. In the course of the reaction, MnO particles precipitate in several special orientations relative to the Cu lattice: “parallel” topotaxy, “twin” topotaxy, and a 55°[110] rotation yielding (111)Cu∥(002)MnO. Each of the three Cu/MnO orientation relationships has a characteristic particle morphology reflecting thermodynamically favourable interface structures. In parallel topotaxy MnO particles preferentially form flat {111}Cu/{111} MnO interfaces with a lattice mismatch of 21%. Although this mismatch is large, the existence of coherence strains in the Cu cannot be excluded. MnO particles in the 55°[110] orientation form regions of semi-coherent Interface where {200}MnO planes face a set of parallel {111} Cu planes with a mismatch of only 6%. This interface variant exhibits equally spaced steps, every 16 to 18 Cu {111} planes. Parallel to every step there is a misfit dislocation in the Cu at a stand-off distance of about 2 Cu {111} spacings. The relationship between structure and energy of the Cu/MnO interface is discussed.

Atomic Resolution Studies of Tilt Grain Boundaries in NiO

1985 ◽  
Vol 60 ◽  
Author(s):  
K. L. Merkle ◽  
J. F. Reddy ◽  
C. L. Wiley ◽  
David J. Smith ◽  
G. J. Wood
Keyword(s):  
Electron Microscopy ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Mirror Symmetry ◽  
High Resolution Electron Microscopy ◽  
Atomic Resolution ◽  
High Angle ◽  
Structural Units ◽  
Atomic Structures ◽  
Resolution Electron

AbstractThe atomic structures of a number of <001> high-angle tilt grain boundaries in NiO have been studied by high-resolution electron microscopy (HREM). Crystal 1inity is always maintained right up to the grain boundary (GB). Grain boundary planes bounded by a (100)-plane are preferred, however symmetrical facets are also found at each misorientation. A tendency to match atomic planes across the GB is not only observed in symmetrical, but also in asymmetrical GBs. Structural units can be clearly recognized in symmetrical GBs. Contrast differences suggest that a multiplicity of structural units exists for some GB configurations. Frequently symmetric GBs also show deviations from mirror symmetry. Multislice simultations indicate that the image contrast associated with HREM GB images is not particularly sensitive to GB relaxation.

Microstructure at the interface between AIN and a Ag–Cu–Ti braze alloy

1990 ◽  
Vol 5 (7) ◽  
pp. 1520-1529 ◽  
Author(s):  
A. H. Carim ◽  
R. E. Loehman
Keyword(s):  
Electron Microscopy ◽  
Thermal Expansion ◽  
Structural Integrity ◽  
Lattice Mismatch ◽  
Braze Alloy ◽  
High Resolution Electron Microscopy ◽  
Nitride Layer ◽  
Orientation Relationships ◽  
Transmission Electron ◽  
Resolution Electron

The joining of aluminum nitride by active metal brazing with a Ag–Cu–Ti foil has been investigated in cross section by transmission electron microscopy. The reaction of AIN with the braze alloy results in the formation of continuous TiN and (Ti, Cu, Al)6N (η-phase) layers at the interface. AIN grains at the interface often display arrays of dislocations, presumably arising from thermal expansion mismatch between the AIN and the TiN (the coefficients of thermal expansion are 43 ⊠ 10−7/°C and 80 ⊠ 10−7/°C, respectively). The adjoining TiN contains small Cu precipitates and may also contain numerous defects. Titanium preferentially penetrates the AIN grain boundaries, resulting in finger-like TiN intrusions into the substrate, which sometimes cover entire AIN grains in a TiN shell. On the other side of the TiN, a continuous layer of equiaxed, defect-free η–nitride grains is found. Beyond this η–nitride layer is the remaining mixture of metallic Ag and Cu. High-resolution electron microscopy demonstrates that the AIN–TiN and TiN–η boundaries are abrupt and contain no additional crystalline or amorphous intervening phases. Particular orientation relationships are occasionally observed at the AIN–TiN interface; these are not always the ones that produce the minimum lattice mismatch. The implications of the observed morphology with respect to the reaction sequence, transitional phases, and structural integrity of the joint are discussed.

A New Method of Preparing Tilt Boundaries for High Resolution Electron Microscopy

1987 ◽  
Vol 115 ◽  
Author(s):  
William Krakow ◽  
Victor Castańo
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
High Resolution ◽  
Grain Boundaries ◽  
High Resolution Electron Microscopy ◽  
Zone Axis ◽  
New Method ◽  
Lateral Overgrowth ◽  
Resolution Electron ◽  
Tilt Boundaries

ABSTRACTA new method of preparing bicrystal substrates of NaCl with a common tilt zone axis has been developed. Upon a lateral overgrowth of NaCl, bridging the two mechanically polished and oriented crystals, very thin films can then be vapor deposited. Au bicrystals of ∼ 75Å thickness and b.c.c. Cr films of similar thickness with grain boundaries have been fabricated.

Morphology and orientation of ultrafine Y2O3 precipitates in YBa2Cu3O7-x thin films

1992 ◽  
Vol 50 (1) ◽  
pp. 242-243
Author(s):  
P. Lu ◽  
J. Zhao ◽  
C.S. Chern ◽  
Y.Q. Li ◽  
B. Gallois ◽  
...  
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Thin Films ◽  
Film Growth ◽  
Chemical Vapor ◽  
Resolution Limit ◽  
Orientation Relationships ◽  
Ion Milling ◽  
Cross Sectional ◽  
Ybco Thin Films

Yttrium-rich YBa2Cu3O7-x (YBCO) thin films grown by plasma-enhanced metalorganic chemical vapor deposition (PE-MOCVD), have been reported to have high critical current densities (Jc) of > l×106A/cm2 at 77K. Electron microscopy has been used to understand how excess Y is incorporated into thin film microstructures without affecting their superconducting properties. In this work, we report identification of small Y2O3 precipitates, their morphologies and orientation relationships in YBCO thin films.Details of thin film growth process have been reported elsewhere. The films were examined both in planar and in cross-sectional view by electron microscopy. TEM samples were prepared by conventional mechanical polishing and ion milling techniques. An ISI-002B high resolution electron microscope with a resolution limit of ∼0.18 nm at 200keV was used for observations.

Direct Correlation of Transport Properties and Microstructure In Y1Ba2Cu3O7-x Thin Film Grain Boundaries

1994 ◽  
Vol 357 ◽  
Author(s):  
B. V. Vuchic ◽  
K. L. Merkle ◽  
D. B. Buchholz ◽  
R. P. H. Chang ◽  
L. D. Marks
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Grain Boundaries ◽  
High Resolution Electron Microscopy ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Current Voltage ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis ◽  
The Individual

AbstractIndividual 45° [001] tilt grain boundaries in Y1Ba2Cu3O7-x thin films grown on biepitaxial substrates were studied. The thin films were grown using both pulsed organometallic beam epitaxy (POMBE) and laser ablation. Transport characteristics of the individual grain boundaries were measured including resistance - temperature (R-T) and current - voltage (I-V) dependencies with and without an applied magnetic field. In order to elucidate possible structural origins of the differences in transport behavior, the same grain boundaries which were electrically characterized were subsequently thinned for electron-microscopy analysis. Transmission-electron-microscopy and high-resolution-electron-microscopy were used to structurally characterize the grain boundaries. The macroscopic and microscopic structures of two boundaries, a nominally resistive and a superconducting grain boundary, are compared.

High Resolution Electron Microscopy (HREM) Study of Chemically Vapor Deposited Polycrystalline Si1-xGex Thin Films

2000 ◽  
Vol 609 ◽  
Author(s):  
W. Qin ◽  
D. G. Ast ◽  
T. I. Kamins
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
High Resolution ◽  
Repeat Unit ◽  
High Resolution Electron Microscopy ◽  
Second Order ◽  
Plan View ◽  
Atomic Structures ◽  
Resolution Electron ◽  
Polysilicon Films

ABSTRACTThe microstructure of polysilicon and Si0.69Ge0.31 thin films, grown by chemical-vapordeposition (CVD) on oxidized silicon wafers covered with a very thin polysilicon seed layer, was investigated using high-resolution electron microscopy (HREM). The plan-view HREM images showed that polysilicon films contained less substructure inside grains and had fewer multiple twins and more extended twin bands than Si0.69Ge0.31. On the other hand, only SiGe contained multiple twins with five-fold symmetry. The atomic model of the second-order symmetric twin boundary proposed for Si and based on the insertion of five-member and seven-membered rings was found to describe the atomic structures of second-order symmetric twin boundaries in Si0.69Ge0.31 as well. Within the accuracy of HREM, the repeat unit of the boundary was the same in Si0.69Ge0.31 and Si.

Textured Pb(Zr0.54Ti0.46)O3 Thin Films with YBa2Cu3O7-δ and Yttria-Stabilized Zirconia Buffer Layers on (001)Si

1993 ◽  
Vol 310 ◽  
Author(s):  
Tsvetanka Zheleva ◽  
P. Tiwari ◽  
J. Narayan
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Yttria Stabilized Zirconia ◽  
Buffer Layers ◽  
X Ray Diffraction ◽  
Orientation Relationships ◽  
Stabilized Zirconia ◽  
X Ray

AbstractCharacteristics of textured Pb(Zr0.54Ti0.46)O3 (PZT) thin films on (001)Si with YBa2Cu3O7-δ (YBCO) and yttria-stabilized zirconia (YSZ) buffer layers have been studied using X-ray diffraction and high resolution electron microscopy techniques. Excimer KrF laser has been used for deposition of PZT, YBCO and YSZ thin films. The YBCO layer was utilized to provide a seed for PZT growth, while YSZ layer acted as a seed and a buffer layer for the growth of YBCO on (001)Si. High-resolution transmission electron microscopy (HRTEM) and X-ray diffraction were used to determine the texture and the nature of defects, interfaces and grain boundaries. Predominant orientation relationships were found to be [001]PZT//[001]YBCO; [001]YBCO//[001]YSZ; and [001]YSZ//[001]Si.

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