Comparison of the Interface and Surface Morphologies of Zirconium and Titanium Silicides on Silicon

1992 ◽  
Vol 260 ◽  
Author(s):  
C. A. Sukow ◽  
R. J. Nemanich
Keyword(s):  
Island Formation ◽  
Leed Pattern ◽  
Liquid Model ◽  
Surface Morphologies

ABSTRACTThe morphology of zirconium suicide grown on Si(111) is investigated and compared to that of titanium suicide on Si(111) and (100). Zirconium was deposited on atomically clean silicon in UHV, and the suicide was formed by postdeposition annealing. ZrSi2 films formed from ≤100 Å of Zr deposited on Si(111) remained continuous for anneals of 400°C to 700°C. A film formed from 50 Å of Zr on Si(111) remained continuous for anneals up to 800°C, at which point the reappearance of a partial 7×7 LEED pattern indicated island formation. The interfaces of the films, studied by TME, show roughening after suicide formation. These results are compared and contrasted with the islanding behavior of titanium suicides, and analyzed in terms of a liquid-liquid model previously used with TiSi2.

Surface Morphologies and Interfaces of TiSi2 Formed from UHV Deposited Ti on Si

1989 ◽  
Vol 160 ◽  
Author(s):  
Hyeongtag Jeon ◽  
R. J. Nemanich ◽  
J.W. Honeycutt ◽  
G. A. Rozgonyi
Keyword(s):  
Room Temperature ◽  
Ex Situ ◽  
Island Formation ◽  
Surface And Interface ◽  
Angle Measurements ◽  
Contact Angle Measurements ◽  
Liquid Model ◽  
Surface Morphologies ◽  
Substrate Temperatures

AbstractThe island formation of TiSi2 and the surface morphologies and interfaces of TiSi2 on Si have been examined and related to the surface and the interface energies. Ti (200Å and 400Å) films were deposited on clean, reconstructed Si(100) and Si(111) substrates at room temperature and also at high substrate temperatures (500°C~800°C). The TiSi2 formation process is monitored with in-situ LEED and AES and the surface morphologies and interfaces are examined with ex-situ SEM and TEM. For annealing to temperatures such that the C54 phase forms, the results indicate island formation with clean reconstructed substrate regions between the islands. The TiSi2 islands show different morphology on the (100) and (111) oriented substrates. The mechanism of TiSi2 island formation is described in terms of a liquid-liquid model, and the surface and interface energies for the TiSi2 island are determined from contact angle measurements.

The Possibilities for Analytical Methods in Photoemission and Low-Energy Electron Microscopy

1990 ◽  
Vol 48 (1) ◽  
pp. 348-349
Author(s):  
Ernst Bauer
Keyword(s):  
Chemical Characterization ◽  
Emission Angle ◽  
Relative Energy ◽  
Objective Lens ◽  
Chemical Information ◽  
Magnetic Lens ◽  
Incident Intensity ◽  
X Ray ◽  
Leed Pattern ◽  
Image Position

One of the major shortcomings of conventional PEEM and of LEEM is the lack of chemical information about the surface. Although the imaging of the LEED pattern in the back focal plane of the objective lens of a LEEM instrument allows chemical characterization via the crystalline structure derived from the LEED pattern, this method fails in the absence of a characteristic LEED pattern. Direct information about the atomic composition of the surface is then needed which can be best obtained from inner shell electrons either directly by x-ray-induced photoemission (XPEEM) or by x-ray- or electron-induced Auger electron emission (AEEM). These modes of excitation and imaging can be combined with conventional PEEM and LEEM in one instrument which is presently being developed. Thus a complete structural and chemical characterization becomes possible in one instrument, with parallel detection and high resolution.In contrast to LEEM, in which up to more than 50% of the incident intensity is available for image formation, the intensity of the emitted electrons is much lower in XPEEM and AEEM and the signal is much lower than the background in AEEM. Therefore, intensity I and resolution d have to be optimized simultaneously which is best done by maximizing Q = I/d2 with respect to maximum emission angle α and relative energy distribution ε = ΔVo/V accepted by the instrument. For a well-designed magnetic lens section of the cathode lens its aberrations are determined by the accelerating field F in front of the specimen. For a homogeneous accelerating field F and a cosine emission distribution one obtains for the optimum α and ε values αo,εo a radius of the minimum disc of confusion of

Transmission Electron Microscopy characterization of epitaxial III-V semiconductor thin films grown on Si(100) by ion-assisted deposition

1990 ◽  
Vol 48 (4) ◽  
pp. 686-687
Author(s):  
L. Hultman ◽  
C.-H. Choi ◽  
R. Kaspi ◽  
R. Ai ◽  
S.A. Barnett
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ion Irradiation ◽  
High Energy ◽  
Nucleation Mechanism ◽  
Layer By Layer ◽  
Extended Defect ◽  
Island Formation ◽  
Si Substrates ◽  
Transmission Electron

III-V semiconductor films nucleate by the Stranski-Krastanov (SK) mechanism on Si substrates. Many of the extended defects present in the films are believed to result from the island formation and coalescence stage of SK growth. We have recently shown that low (-30 eV) energy, high flux (4 ions per deposited atom), Ar ion irradiation during nucleation of III-V semiconductors on Si substrates prolongs the 1ayer-by-layer stage of SK nucleation, leading to a decrease in extended defect densities. Furthermore, the epitaxial temperature was reduced by >100°C due to ion irradiation. The effect of ion bombardment on the nucleation mechanism was explained as being due to ion-induced dissociation of three-dimensional islands and ion-enhanced surface diffusion.For the case of InAs grown at 380°C on Si(100) (11% lattice mismatch), where island formation is expected after ≤ 1 monolayer (ML) during molecular beam epitaxy (MBE), in-situ reflection high-energy electron diffraction (RHEED) showed that 28 eV Ar ion irradiation prolonged the layer-by-layer stage of SK nucleation up to 10 ML. Otherion energies maintained layer-by-layer growth to lesser thicknesses. The ion-induced change in nucleation mechanism resulted in smoother surfaces and improved the crystalline perfection of thicker films as shown by transmission electron microscopy and X-ray rocking curve studies.

Defect morphology in thick relaxed layers of InGaAs on GaAs

1990 ◽  
Vol 48 (4) ◽  
pp. 668-669
Author(s):  
R H Dixon ◽  
P Kidd ◽  
P J Goodhew
Keyword(s):  
Electron Microscopy ◽  
Surface Morphology ◽  
Growth Conditions ◽  
X Ray Diffraction ◽  
Double Crystal ◽  
Strained Layers ◽  
Good Surface ◽  
Transmission Electron ◽  
Device Structures ◽  
Surface Morphologies

Thick relaxed InGaAs layers grown epitaxially on GaAs are potentially useful substrates for growing high indium percentage strained layers. It is important that these relaxed layers are defect free and have a good surface morphology for the subsequent growth of device structures.3μm relaxed layers of InxGa1-xAs were grown on semi - insulating GaAs substrates by Molecular Beam Epitaxy (MBE), where the indium composition ranged from x=0.1 to 1.0. The interface, bulk and surface of the layers have been examined in planar view and cross-section by Transmission Electron Microscopy (TEM). The surface morphologies have been characterised by Scanning Electron Microscopy (SEM), and the bulk lattice perfection of the layers assessed using Double Crystal X-ray Diffraction (DCXRD).The surface morphology has been found to correlate with the growth conditions, with the type of defects grown-in to the layer (e.g. stacking faults, microtwins), and with the nature and density of dislocations in the interface.

Electron Optical Study of Surface Morphologies of Crystals

1980 ◽  
Vol 38 ◽  
pp. 376-377
Author(s):  
Sumio Iijima ◽  
Tung Hsu
Keyword(s):  
Thin Film ◽  
Optical Study ◽  
Regular Array ◽  
Surface Steps ◽  
Diffracted Waves ◽  
Image Position ◽  
Surface Morphologies

Suppose the thickness of a thin film of a crystal varies periodically like a regular array of surface steps, kinematical intensities of diffracted waves from this crystal are modulated by a shape transform,

Effects of Wet Chemical Oxidation on Surface Functionalization and Morphology of Highly Oriented Pyrolytic Graphite

2020 ◽  
Author(s):  
Mikhail Trought ◽  
Isobel Wentworth ◽  
Timothy Leftwich ◽  
Kathryn Perrine
Keyword(s):  
Surface Functionalization ◽  
Functional Group ◽  
Pyrolytic Graphite ◽  
Surface Oxidation ◽  
Chemical Oxidation ◽  
Synthesis Methods ◽  
Acid Solutions ◽  
Highly Oriented Pyrolytic Graphite ◽  
Wet Chemical ◽  
Surface Morphologies

The knowledge of chemical functionalization for area selective deposition (ASD) is crucial for designing the next generation heterogeneous catalysis. Surface functionalization by oxidation was studied on the surface of highly oriented pyrolytic graphite (HOPG). The HOPG surface was exposed to with various concentrations of two different acids (HCl and HNO3). We show that exposure of the HOPG surface to the acid solutions produce primarily the same -OH functional group and also significant differences the surface topography. Mechanisms are suggested to explain these strikingly different surface morphologies after surface oxidation. This knowledge can be used to for ASD synthesis methods for future graphene-based technologies.

Bubble Electrospinning and Bubble-Spun Nanofibers

2020 ◽  
Vol 14 (1) ◽  
pp. 10-13 ◽  
Author(s):  
Lynn Y. Wan
Keyword(s):  
Surface Tension ◽  
Low Energy ◽  
Efficient Technology ◽  
High Productivity ◽  
Needleless Electrospinning ◽  
Polymeric Nanofibers ◽  
Low Energy Consumption ◽  
Potential Applications ◽  
Surface Morphologies ◽  
Unique Surface

Electrospinning is a highly efficient technology for fabrication of a wide variety of polymeric nanofibers. However, the development of traditional needle-based electrospinning has been hampered by its low productivity and need of tedious work dealing with needles cleaning, installation and uninstallation. As one of the most promising needleless electrospinning means, bubble electrospinning is known for its advantages of high productivity and relatively low energy consumption due to the introduction of a third force, air flow, as a major force overcoming the surface tension. In this paper, the restrictions of conventional electrospinning and the advantages of needleless electrospinning, especially the bubble electrospinning were elaborated. Reports and patents on bubble-spun nanofibers with unique surface morphologies were also reviewed in respect of their potential applications.

scholarly journals Numerical Simulation of Effect of Different Initial Morphologies on Melt Hydrodynamics in Laser Polishing of Ti6Al4V

Micromachines ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 581
Author(s):  
Kai Li ◽  
Zhenyu Zhao ◽  
Houming Zhou ◽  
Hao Zhou ◽  
Jie Yin ◽  
...  
Keyword(s):  
Flow Behavior ◽  
Processing Parameters ◽  
Surface Finishing ◽  
Polished Surface ◽  
Laser Polishing ◽  
Starting Position ◽  
Double Spiral ◽  
The Difference ◽  
Thermocapillary Forces ◽  
Surface Morphologies

As a surface finishing technique for rapid remelting and re-solidification, laser polishing can effectively eliminate the asperities so as to approach the feature size. Nevertheless, the polished surface quality is significantly sensitive to the processing parameters, especially with respect to melt hydrodynamics. In this paper, a transient two-dimensional model was developed to demonstrate the molten flow behavior for different surface morphologies of the Ti6Al4V alloy. It is illustrated that the complex evolution of the melt hydrodynamics involving heat conduction, thermal convection, thermal radiation, melting and solidification during laser polishing. Results show that the uniformity of the distribution of surface peaks and valleys can improve the molten flow stability and obtain better smoothing effect. The high cooling rate of the molten pool resulting in a shortening of the molten lifetime, which prevents the peaks from being removed by capillary and thermocapillary forces. It is revealed that the mechanism of secondary roughness formation on polished surface. Moreover, the double spiral nest Marangoni convection extrudes the molten to the outsides. It results in the formation of expansion and depression, corresponding to nearby the starting position and at the edges of the polished surface. It is further found that the difference between the simulation and experimental depression depths is only about 2 μm. Correspondingly, the errors are approximately 8.3%, 14.3% and 13.3%, corresponding to Models 1, 2 and 3, respectively. The aforementioned results illustrated that the predicted surface profiles agree reasonably well with the experimentally measured surface height data.

scholarly journals Expanding 3D Nanoprinting Performance by Blurring the Electron Beam

Micromachines ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 115
Author(s):  
Lukas Seewald ◽  
Robert Winkler ◽  
Gerald Kothleitner ◽  
Harald Plank
Keyword(s):  
Electron Beam ◽  
Direct Write ◽  
Design Flexibility ◽  
Individual Branch ◽  
Inclination Angles ◽  
3D Architecture ◽  
20 Nm ◽  
Surface Morphologies ◽  
Nm Range ◽  
Mechanical Rigidity

Additive, direct-write manufacturing via a focused electron beam has evolved into a reliable 3D nanoprinting technology in recent years. Aside from low demands on substrate materials and surface morphologies, this technology allows the fabrication of freestanding, 3D architectures with feature sizes down to the sub-20 nm range. While indispensably needed for some concepts (e.g., 3D nano-plasmonics), the final applications can also be limited due to low mechanical rigidity, and thermal- or electric conductivities. To optimize these properties, without changing the overall 3D architecture, a controlled method for tuning individual branch diameters is desirable. Following this motivation, here, we introduce on-purpose beam blurring for controlled upward scaling and study the behavior at different inclination angles. The study reveals a massive boost in growth efficiencies up to a factor of five and the strong delay of unwanted proximal growth. In doing so, this work expands the design flexibility of this technology.

scholarly journals Electrospun Nanofibrous Membranes for Tissue Engineering and Cell Growth

2021 ◽  
Vol 11 (15) ◽  
pp. 6929
Author(s):  
Ewin Tanzli ◽  
Andrea Ehrmann
Keyword(s):  
Tissue Engineering ◽  
Cell Growth ◽  
Polymer Blends ◽  
Mammalian Cells ◽  
Biological Properties ◽  
Specific Substrate ◽  
Electrospun Nanofiber ◽  
Materials Used ◽  
Nanofiber Mats ◽  
Surface Morphologies

In biotechnology, the field of cell cultivation is highly relevant. Cultivated cells can be used, for example, for the development of biopharmaceuticals and in tissue engineering. Commonly, mammalian cells are grown in bioreactors, T-flasks, well plates, etc., without a specific substrate. Nanofibrous mats, however, have been reported to promote cell growth, adhesion, and proliferation. Here, we give an overview of the different attempts at cultivating mammalian cells on electrospun nanofiber mats for biotechnological and biomedical purposes. Starting with a brief overview of the different electrospinning methods, resulting in random or defined fiber orientations in the nanofiber mats, we describe the typical materials used in cell growth applications in biotechnology and tissue engineering. The influence of using different surface morphologies and polymers or polymer blends on the possible application of such nanofiber mats for tissue engineering and other biotechnological applications is discussed. Polymer blends, in particular, can often be used to reach the required combination of mechanical and biological properties, making such nanofiber mats highly suitable for tissue engineering and other biotechnological or biomedical cell growth applications.

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