Interface Morphology, Nucleation and Island Formation of Tisi2 on Si(111).

1990 ◽  
Vol 181 ◽  
Author(s):  
Hyeongtag Jeon ◽  
C. A. Sukow ◽  
J. W. Honeycutt ◽  
T. P. Humphreys ◽  
R. J. Nemanich ◽  
...  
Keyword(s):  
High Vacuum ◽  
Ultra High Vacuum ◽  
Nucleation Theory ◽  
Formation Mechanisms ◽  
Silicon Substrates ◽  
Interface Morphology ◽  
Free Energies ◽  
Island Formation ◽  
Flat Interface ◽  
Interface Structures

ABSTRACTIn this study we investigate the formation mechanisms and morphology of TiSi2 formed by deposition of Ti on atomically clean silicon substrates. Ti films of 50–400 Å thickness were deposited in ultra-high vacuum on Si (111) wafers and annealed to temperatures between 500–900°C. Films were monitored in situ with AES and LEED, and post preparation characterization was accomplished with SEM, TEM and Raman scattering. The results show that for films of thickness ≤, 100 Å the C49 TiSi2 phase is stable over the entire 600-800°C temperature range. However, for films of 200-400 Å thickness, the C49 to C54 phase transition occurs at temperatures varying from 700 to 800°C dependent upon film thickness. The high temperature annealing results in flat interface structures, and island formation is observed for all films with the C54 structure. The interface morphology and the mechanisms of TiSi2 island and phase formation are discussed in terms of surface and bulk free energies considerations based on nucleation theory.

Formation Mechanisms for Multiply Twinned Particles During Nucleation in the Au/MICA System

1975 ◽  
Vol 33 ◽  
pp. 84-85
Author(s):  
Eal H. Lee ◽  
Helmut Poppa
Keyword(s):  
Deposition Time ◽  
High Vacuum ◽  
Dark Field ◽  
Ultra High Vacuum ◽  
Formation Mechanisms ◽  
Heat Treated ◽  
Cluster Density ◽  
Diffraction Patterns ◽  
Crystal Particle ◽  
Multiply Twinned Particles

The formation of thin films of gold on mica has been studied in ultra-high vacuum (5xl0-10 torr) . The mica substrates were heat-treated for 24 hours at 375°C, cleaved, and annealed for 15 minutes at the deposition temperature of 300°C prior to deposition. An impingement flux of 3x1013 atoms cm-2 sec-1 was used. These conditions were found to give high number densities of multiple twin particles and are based on a systematic series of nucleation experiments described elsewhere. Individual deposits of varying deposition time were made and examined by bright and dark field TEM after "cleavage preparation" of highly transparent specimens. In the early stages of growth, the films generally consist of small particles which are either single crystals or multiply twinned; a strong preference for multiply twinned particles was found whenever the particle number densities were high. Fig. 1 shows the stable cluster density ns and the variation with deposition time of multiple twin particle and single crystal particle densities, respectively. Corresponding micrographs and diffraction patterns are shown in Fig. 2.

HREM Observations of Mg2Si-Based Multilayers for Soft X-Ray Optics

1991 ◽  
Vol 49 ◽  
pp. 906-907
Author(s):  
A. R. Modak ◽  
David J. Smith ◽  
Z. G. Li ◽  
P. Boher ◽  
Ph. Houdy
Keyword(s):  
High Vacuum ◽  
Rf Sputtering ◽  
Ultra High Vacuum ◽  
Silicon Substrates ◽  
Ray Optics ◽  
X Ray ◽  
Long Period ◽  
The Past ◽  
X Ray Scattering ◽  
Short Period

Multilayers fabricated with alternating materials having significant differences in X-ray scattering powers are being investigated for applications in soft X-ray optics. Multilayers consisting of combinations of W, Rh, Fe, Si3N4, SiO2 and Si, C, B4C have been studied in the past. Mg2Si based multilayer structures are theoretically efficient reflectors of wavelengths above the Mg-Kα line (9.89 Å) and the Mg-Lα line (251.5 Å) because of their low absorption in the respective wavelength regimes due to the presence of magnesium. In the present study, Mg2Si based multilayers fabricated on silicon substrates by ultra high vacuum rf sputtering have been characterized by HREM. W, Si, and Mg2Si targets in conjunction with the introduction of nitrogen were employed to deposit alternate Mg2Si and W or Si3N4 layers. We report here our preliminary observations of a characteristic short period W/Mg2Si layered structure used above the Mg-Kα line and two long period multilayers based on W/Mg2Si and Si3N4/Mg2Si used above the Mg-Lα line.

Epitaxial CeO2 on Silicon Substrates and the Potential of Si/CeO2/Si for SOI Structures

1997 ◽  
Vol 474 ◽  
Author(s):  
A. H. Morshed ◽  
S. X. Liu ◽  
R. Leonard ◽  
F. G. Mcintosh ◽  
N. A. El-Masry ◽  
...  
Keyword(s):  
Optical Properties ◽  
Single Crystal ◽  
High Vacuum ◽  
Silicon On Insulator ◽  
Ultra High Vacuum ◽  
Vacuum System ◽  
Silicon Substrates ◽  
Cubic Structure ◽  
Lattice Matched ◽  
Initial Results

ABSTRACTCeO2 is nearly lattice matched to Si and has the CaF2 cubic structure thus it offers the potential for the epitaxial growth of an insulating film on Si. Laser ablation of a CeO2 target in an ultra high vacuum system was used for the deposition of single crystal CeO2. The effect of post growth thermal and rapid thermal annealing in O2, N2 and Ar atmosphere was found to have pronounced effects on the electrical properties measured by C-V and the optical properties measured by photoluminescence.We report on our initial results for the growth of epitaxial Si on the deposited CeO2 using low pressure CVD. Both RHEED and TEM studies showed that single crystal epitaxial Si was deposited on CeO2. The details of the Si deposition on CeO2 films for potential of SOI (silicon on insulator) structures will be discussed.

Study on the interface morphology in the induction welding joint of PEEK plate at low power

2020 ◽  
Vol 40 (5) ◽  
pp. 432-439 ◽  
Author(s):  
Wanping Ma ◽  
Xiaohong Zhan ◽  
Hongyan Yang ◽  
Hengchang Bu ◽  
Yun Li ◽  
...  
Keyword(s):  
Low Power ◽  
Tensile Fracture ◽  
Formation Mechanisms ◽  
Interface Morphology ◽  
Metal Mesh ◽  
Poly Ether Ether Ketone ◽  
Induction Components ◽  
Mechanical Tensile ◽  
Interface Structures ◽  
Micro Structures

AbstractInduction welding is an important joining technique with potentially significant application in the connection of the Poly Ether Ether Ketone (PEEK). The present research employs the metal mesh as induction components into the induction welding of PEEK plate to PEEK plate at low power successfully. Besides, the examinations and analyses of macro/micro-structures, energy dispersive spectroscopy (EDS) and mechanical tensile properties of the joints are conducted. Meanwhile, the characteristics and formation mechanisms of the lap-welded interface structures are interpreted in detail. The results indicate that the interface morphology of the welded joint is of high quality at low power, which most of the interface area is tightly connected due to the element diffusion. Besides, the connection mechanism of the joint is bonding connection and mechanical engagement, which plays a major role in a great performance joint. Furthermore, the tensile fracture of the joint occurs in the heat-affected zone, which contributes to a high joint tensile strength.

Thin Pyrolytic Graphite Films for Electron Microscope Substrates

1971 ◽  
Vol 29 ◽  
pp. 226-227 ◽  
Author(s):  
George H. N. Riddle ◽  
Benjamin M. Siegel
Keyword(s):  
Vacuum Chamber ◽  
Pyrolytic Graphite ◽  
High Vacuum ◽  
Dark Field ◽  
Ultra High Vacuum ◽  
Graphite Substrate ◽  
Nickel Substrate ◽  
Routine Procedure ◽  
Field Electron Microscopy ◽  
Dark Field Electron

A routine procedure for growing very thin graphite substrate films has been developed. The films are grown pyrolytically in an ultra-high vacuum chamber by exposing (111) epitaxial nickel films to carbon monoxide gas. The nickel serves as a catalyst for the disproportionation of CO through the reaction 2C0 → C + CO2. The nickel catalyst is prepared by evaporation onto artificial mica at 400°C and annealing for 1/2 hour at 600°C in vacuum. Exposure of the annealed nickel to 1 torr CO for 3 hours at 500°C results in the growth of very thin continuous graphite films. The graphite is stripped from its nickel substrate in acid and mounted on holey formvar support films for use as specimen substrates.The graphite films, self-supporting over formvar holes up to five microns in diameter, have been studied by bright and dark field electron microscopy, by electron diffraction, and have been shadowed to reveal their topography and thickness. The films consist of individual crystallites typically a micron across with their basal planes parallel to the surface but oriented in different, apparently random directions about the normal to the basal plane.

A High Voltage Electron Microscopy Study of Sub-Oxide Formation in Vanadium

1971 ◽  
Vol 29 ◽  
pp. 212-213
Author(s):  
R. H. Geiss ◽  
R. L. Ladd ◽  
K. R. Lawless
Keyword(s):  
High Vacuum ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Ultra High Vacuum ◽  
Pure Oxygen ◽  
Pressure Oxidation ◽  
High Voltage Electron Microscopy ◽  
Oxidation Study ◽  
Voltage Electron ◽  
Good Agreement

Detailed electron microscope and diffraction studies of the sub-oxides of vanadium have been reported by Cambini and co-workers, and an oxidation study, possibly complicated by carbon and/or nitrogen, has been published by Edington and Smallman. The results reported by these different authors are not in good agreement. For this study, high purity polycrystalline vanadium samples were electrochemically thinned in a dual jet polisher using a solution of 20% H2SO4, 80% CH3OH, and then oxidized in an ion-pumped ultra-high vacuum reactor system using spectroscopically pure oxygen. Samples were oxidized at 350°C and 100μ oxygen pressure for periods of 30,60,90 and 160 minutes. Since our primary interest is in the mechanism of the low pressure oxidation process, the oxidized samples were cooled rapidly and not homogenized. The specimens were then examined in the HVEM at voltages up to 500 kV, the higher voltages being necessary to examine thick sections for which the oxidation behavior was more characteristic of the bulk.

The High Resolution Scanning Transmission Electron Microscope

1974 ◽  
Vol 32 ◽  
pp. 316-317
Author(s):  
A. V. Crewe
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
High Vacuum ◽  
Scanning Transmission Electron Microscope ◽  
Ultra High Vacuum ◽  
Resolving Power ◽  
Imaging Characteristics ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
The Moment

The high resolution STEM is now a fact of life. I think that we have, in the last few years, demonstrated that this instrument is capable of the same resolving power as a CEM but is sufficiently different in its imaging characteristics to offer some real advantages.It seems possible to prove in a quite general way that only a field emission source can give adequate intensity for the highest resolution^ and at the moment this means operating at ultra high vacuum levels. Our experience, however, is that neither the source nor the vacuum are difficult to manage and indeed are simpler than many other systems and substantially trouble-free.

Structure of Palladium Single-Crystal Films Prepared by Flash Evaporation onto (001) NaCl Substrates

1970 ◽  
Vol 28 ◽  
pp. 456-457
Author(s):  
L. E. Murr ◽  
G. Wong
Keyword(s):  
Single Crystal ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
High Rate ◽  
Flash Evaporation ◽  
Optimum Load ◽  
Single Crystal Films ◽  
Crystal Films ◽  
A Current

Palladium single-crystal films have been prepared by Matthews in ultra-high vacuum by evaporation onto (001) NaCl substrates cleaved in-situ, and maintained at ∼ 350° C. Murr has also produced large-grained and single-crystal Pd films by high-rate evaporation onto (001) NaCl air-cleaved substrates at 350°C. In the present work, very large (∼ 3cm2), continuous single-crystal films of Pd have been prepared by flash evaporation onto air-cleaved (001) NaCl substrates at temperatures at or below 250°C. Evaporation rates estimated to be ≧ 2000 Å/sec, were obtained by effectively short-circuiting 1 mil tungsten evaporation boats in a self-regulating system which maintained an optimum load current of approximately 90 amperes; corresponding to a current density through the boat of ∼ 4 × 104 amperes/cm2.

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