Analysis of co-deposited Ti-Hf thin film on (0001)6H-SiC by HREM, energy-selected and hollow-cone images

1994 ◽  
Vol 52 ◽  
pp. 978-979
Author(s):  
J. S. Bow
Keyword(s):  
Thin Film ◽  
Solid Solution ◽  
Lattice Parameter ◽  
Dark Field ◽  
Electron Beam Evaporation ◽  
Structural Defects ◽  
Misfit Dislocations ◽  
Hollow Cone ◽  
Chemical Homogeneity ◽  
Dark Field Imaging

Solid solution binary alloys are attractive for defect-free thin film semiconductor contacts because lattice matching can be obtained by composition adjustment, but chemical homogeneity is required. Highly composition sensitive energy-selected and hollow cone (HC) dark field imaging were evaluated for heterogeneity detection in Ti-Hf films using an Ω filter/Zeiss 912 TEM. Conventional HREM, which relatively insensitive to spatial composition variations in this case, was used to observe structural defects in the films near the interfaces.Thin films of pure Ti deposited via UHV electron beam evaporation at room temperature on n-type, vicinal (0001) 6H-SiC showed good epitaxy. This contact displayed rectifying characteristics. The interface was both structurally and chemically sharp. However, misfit dislocations at “stand off” positions were found, due to 4 % mismatch between the basal parameters of Ti and SiC. same column with Ti in the periodic table and has hexagonal crystal structure, but larger lattice parameter (aHf = 3.196 Å, and aTi = 2.950 Å). The Ti-Hf solid solution system obeys Vergard's law well, that is, the lattice parameters of this alloy change linearly with composition.

Calculation Of Stem Dark-Field Images

1977 ◽  
Vol 35 ◽  
pp. 192-193
Author(s):  
J. Fertig ◽  
H. Rose
Keyword(s):  
High Resolution Electron Microscopy ◽  
Dark Field ◽  
Angular Width ◽  
Hollow Cone ◽  
Dark Field Imaging ◽  
Dark Field Micrograph ◽  
Resolution Electron ◽  
Detector Geometry ◽  
Annular Detector ◽  
Organometallic Molecules

Dark-field imaging is a promising procedure to visualize single atoms in high resolution electron microscopy. The quality of a dark-field micrograph depends to a large extent on the illumination mode for the CTEM or on the detector geometry for the STEM. The most commonly used dark-field modes are: CTEM with axial, tilted, or hollow-cone illumination and STEM with an annular detector limited by the angles and θ1-θ2. The STEM is equivalent to a CTEM which uses hollow-cone illumination of finite angular width (limiting angles θ1, θ2). the following we always assume θ2 = п/2.The three CTEM imaging modes have been investigated theoretically by several authors. Krakow (1) computed dark-field images of small organometallic molecules assuming tilted illumination. However, he could not achieve results for hollow-cone illumination because his computing method was too timeconsuming. Hoch (2) calculated images of model objects under axialy tilted, and hollow-cone illumination of infinitely small angular widthy applying the fast Fourier transform technique.

High-Resolution Bright-Field and Dark-Field Hollow Cone Illumination

1990 ◽  
Vol 48 (1) ◽  
pp. 36-37
Author(s):  
R.A. Herring ◽  
M.E. Twigg
Keyword(s):  
Large Angle ◽  
Dark Field ◽  
Hollow Cone ◽  
Contrast Imaging ◽  
Lattice Image ◽  
Dark Field Imaging ◽  
Annular Dark Field ◽  
Lattice Images ◽  
Z Contrast ◽  
Field Imaging

Hollow cone illumination using a large C2 blocked-aperture (bl apt) in the conventional TEM (CTEM) can remove the beams within the zero-order Laue zone (ZOLZ) thereby making lattice images more simply interpretable. Dark-field (DF) hollow cone illumination has the added advantage of enhancing the Z-contrast within the lattice image, since the electrons contributing to the image must be scattered over a large angle (approximately 10 mrad). Both of these imaging methods have been explored, using a 600 um C2 bl apt and objective aperture sizes of 70, 20 and 10 um, and are reported in this paper.Much interest has been generated by the report of Pennycook [1] on STEM Z-contrast imaging using annular dark-field. In earlier work ,it was noted that CTEM hollow cone imaging and STEM annular dark-field imaging are related via reciprocity [2] (Fig. 1). In addition, Zernike has shown the advantages of hollow cone illumination in optical phase-contrast microscopy [3]. The electron-optical analogues to these optical techniques are now possible because of the low Cs values achieved in modern TEMs.

Tem Investigation of Al0.5Ga0.5As1-y Sby Buffer Layer Systems

1997 ◽  
Vol 484 ◽  
Author(s):  
E. Chen ◽  
J. S. Ahearn ◽  
K. Nichols ◽  
P. Uppal ◽  
D. C. Paine
Keyword(s):  
Buffer Layer ◽  
Active Regions ◽  
Dark Field ◽  
Layer Growth ◽  
Buffer Layers ◽  
Growth Surface ◽  
Threading Dislocation ◽  
Misfit Dislocations ◽  
Plan View ◽  
Dark Field Imaging

AbstractWe report on a TEM study of Sb-adjusted quaternary Al0.5Ga0.5As1-y Sby buffer-layers grown on <001> GaAs substrates. A series of structures were grown by MBE at 470°C that utilize a multilayer grading scheme in which the Sb content of Al0.5Ga0.5As1-ySby is successively increased in a series of eight 125 nm thick layers. Post growth analysis using conventional bright field and weak beam dark field imaging of these buffer layers in cross-section reveals that the interface misfit dislocations are primarily of the 60° type and are distributed through out the interfaces of the buffer layer. Plan view studies show that the threading dislocation density in the active regions of the structure (approximately 2 μm from the GaAs substrate) is 105–6/cm2 which is comparable to equivalent InxGa1−x As buffers. Weak Sb-As compositional modulations with a period of 1.8 nm were observed that provide a marker for establishing the planarity of the growth process. These features reveal that the growth surface remains planar through out the buffer layer growth sequence.

A Study of the MBE Growth of MGO on The FE(001) Surface

1994 ◽  
Vol 357 ◽  
Author(s):  
J.L. Vassent ◽  
M. Dynna ◽  
G. Patrat ◽  
B. Gilles ◽  
A. Marty
Keyword(s):  
Room Temperature ◽  
Lattice Parameter ◽  
Electron Beam Evaporation ◽  
Ex Situ ◽  
Misfit Dislocations ◽  
Mbe Growth ◽  
Plane Lattice ◽  
Pseudomorphic Growth ◽  
Bulk Parameter

AbstractThe deposition of MgO on the Fe(001) surface has been carried out using electron beam evaporation. MgO is observed to grow epitaxially with a 45° rotation between the Fe(001) and MgO(001) unit cell axes. Oscillations in the intensity of the RHEED specular beam are observed at room temperature showing that growth is two-dimensional. The relaxation of the in-plane lattice parameter during the growth at room temperature has been investigated in-situ by measuring the position of the RHEED streaks and ex-situ with GIXD experiments. Pseudomorphic growth is observed up to about five monolayers. Then the in-plane lattice parameter starts to evolve towards the MgO bulk parameter. HREM shows that the relaxation of MgO occurs via the generation of 1/2<011> misfit dislocations which are non-uniformly spaced at the Fe/MgO interface.

Highly dense and compositionally inhomogeneous nano-agglomerates in an epitaxial La0.8Sr0.2MnO3 thin film grown on (100)SrTiO3

2005 ◽  
Vol 20 (3) ◽  
pp. 571-579 ◽  
Author(s):  
Y.L. Zhu ◽  
X.L. Ma ◽  
D.X. Li ◽  
H.B. Lu ◽  
Z.H. Chen ◽  
...  
Keyword(s):  
Thin Film ◽  
Colossal Magnetoresistance ◽  
Molecular Beam ◽  
Compositional Analysis ◽  
Salient Feature ◽  
Dark Field ◽  
Orientation Relationships ◽  
Dark Field Imaging ◽  
Transmission Electron ◽  
Field Imaging

Microstructures in the thin film of La0.8Sr0.2MnO3 grown on (100) SrTiO3 by laser molecular beam epitaxy were characterized by transmission electron microscopy. Highly dense and dimensionally uniform nano-agglomerates were found embedded in thin film of La0.8Sr0.2MnO3. High-angle angular dark-field imaging, elemental mapping, and compositional analysis revealed that the nano-agglomerates are rich in manganese and poor in lanthanum. The ratio of Mn/La in the nano-agglomerates fluctuates. A salient feature of this compositional fluctuation within the nanoscale isthe formation of cubic MnO phase, which appears as the core of the nano-agglomerates.The La0.8Sr0.2MnO3 film is domain-oriented and two domains were identified on the basis of orthorhombic lattice. The orientation relationships between La0.8Sr0.2MnO3 domains and MnO were determined as [010]LSMO,1//[001]MnO and (100)LSMO,1//(110)MnO; [101]LSMO,2//[001]MnO and (010)LSMO,2//(100)MnO. The domain structuresand compositional inhomogeneities within nanoscale result in a textured microstructure, which is one of the most important parameters for tuning electronic properties in colossal magnetoresistance oxides.

scholarly journals Investigation of Ti1-xMoxCoSb Semiconducting Solid Solution

2020 ◽  
Vol 21 (1) ◽  
pp. 73-81
Author(s):  
Yu. Stadnyk ◽  
V. Romaka ◽  
A. Нoryn ◽  
L. Romaka ◽  
V. Krayovskyy ◽  
...  
Keyword(s):  
Solid Solution ◽  
Structural Changes ◽  
Structural Characteristics ◽  
Energy Levels ◽  
Structure Type ◽  
Lattice Parameter ◽  
Structural Defects ◽  
Simultaneous Generation ◽  
Donor And Acceptor ◽  
Thermopower Coefficient

The effect of doping of the TiCoSb compound (MgAgAs structure type) by Mo atoms on the features of the structural characteristics and behavior of the electrokinetic, energetic and magnetic properties of the Ti1-xMoxCoSb semiconducting solid solution (х = 0 - 0.06) in the temperature interval 80 - 400 K was studied. It was shown that including of Mo atoms (rМо= 0.140 nm) in the ToCoSb structure by substitution of Ti atoms (rТі= 0.146 нм) in 4a position is accompanied with non-monotonous variation of the lattice parameter values а(х), indicating unpredictable structural changes. Based on analysis of the variation of the electric resistivity values, thermopower coefficient, magnetic susceptibility and energetic characteristics, it was concluded that simultaneous generation in the crystal of the structural defects of the donor and acceptor nature (donor-acceptor pairs), which generate corresponding energy levels in the band gap of semiconductor and determine its electrical conductivity.

Precipitation and dislocation decoration via extrinsic gettering of Co, Au and Pt by misfit dislocations in Si/Si-2%Ge epitaxy

1989 ◽  
Vol 47 ◽  
pp. 578-579
Author(s):  
D. M. Lee
Keyword(s):  
Imaging Techniques ◽  
Preceding Paper ◽  
Dark Field ◽  
Misfit Dislocations ◽  
Temperature Dependent ◽  
Bright Field ◽  
Dark Field Imaging ◽  
Weak Beam ◽  
Sample Structure ◽  
Field Imaging

Previous work on the gettering activity of a well defined array of buried interfacial misfit dislocations (MDs) showed that the amount of nickel gettered by MD is dominated by the strong temperature-dependent solubility. Precipitation occurs on or in the immediate vicinity of MDs due to nucleation enhancement by strain effects. High temperature 〈1000°C〉 diffusion of gold resulted in the planar colony precipitates on two {111} planes associated with stacking fault formation. In this contribution, we discuss our continuing research pertaining to cobalt, gold (at low temperature), and platinum gettering by MDs which involves studying the nature of dislocation decoration and impurity precipitation in the Si/Si-2%Ge epitaxial system.All the samples used in this study have a buried Si-2%Ge epitaxial layer of ∼ 2 μm thickness.Co, Au and Pt were deliberately diffused into the wafer. The details of the sample structure and preparation are described in a preceding paper. Two-beam bright field and weak-beam dark field imaging techniques were performed on cross-section TEM specimens.

Anomalous Lattice Parameters in Iron-Copper Multilayers

1995 ◽  
Vol 400 ◽  
Author(s):  
S. J. Lloyd ◽  
R. E. Somekh ◽  
W. M. Stobbs
Keyword(s):  
High Resolution Electron Microscopy ◽  
Lattice Parameter ◽  
Growth Direction ◽  
Dark Field ◽  
Elastic Model ◽  
Electron Loss ◽  
Dark Field Imaging ◽  
Iron Copper ◽  
Resolution Electron ◽  
Field Imaging

AbstractX-ray, magnetism and electron loss spectroscopy data were obtained for a series of coherent Fe-Cu face-centred multilayers which suggest that there is a lattice parameter anomaly in the structure. The use of high resolution electron microscopy (HREM) and dark field imaging to measure spacing changes along the layer normal are compared. Experimental dark field images suggest that the Fe has expanded lattice spacings in the growth direction in contradiction to the predictions of a conventional elastic model for a coherent multilayer structure.

Effect of Sputtering Target Power on Preferred Orientation in nc-TiN/a-SiNx Nanocomposite Thin Films

2005 ◽  
Vol 23 ◽  
pp. 175-178 ◽  
Author(s):  
Sam Zhang ◽  
Deen Sun ◽  
Yong Qing Fu ◽  
H. Du ◽  
Qing Zhang
Keyword(s):  
Thin Film ◽  
Solid Solution ◽  
Lattice Parameter ◽  
Preferred Orientation ◽  
Nanocomposite Thin Film ◽  
Sputtering Deposition ◽  
Amorphous Silicon Nitride ◽  
Nanocomposite Thin Films ◽  
Target Power ◽  
The Matrix

Nanocrystalline TiN (or nc-TiN) has been imbedded in amorphous silicon nitride (a-SiNx)matrix to form a nanocomposite thin film (nc-TiN/a-SiNx) via magnetron sputtering deposition on silicon wafer. Two important effects of the Si3N4 sputtering target power on the formation of nc-TiN/a-SiNx have been studied: (1) Aside from forming a-SiNx in the matrix, Si atoms also imbed into TiN to form (Ti,Si)N solid solution crystallites. At low target power, the solid solution is substitutional. With increase of power, the amount of silicon “dissolved” in the TiN crystallite increases, and in the meantime, the interstitial components increase which is manifested in the increase in the TiN lattice parameter. (2) The crystallites have a preferred orientation varying with the deposition target power. As conveniently described by the coefficient of texture, the degree of preferred orientation along [111] direction decreases and finally tails off with increase of power. At the same time, the crystallites orient along [200] and [220] direction and eventually [220] direction dominants.

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