scholarly journals Interface-dominated growth of a metastable novel alloy phase

2005 ◽  
Vol 20 (10) ◽  
pp. 2639-2646 ◽  
Author(s):  
Subhendu Sarkar ◽  
Alokmay Datta ◽  
Purushottam Chakraborty ◽  
Biswarup Satpati
Keyword(s):  
Secondary Ion Mass Spectrometry ◽  
Metastable Phase ◽  
Alloy Film ◽  
Interfacial Region ◽  
Lattice Image ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Interfacial Confinement ◽  
The Individual ◽  
Almost All

A new D023 metastable phase of Cu3Au was found to grow at the interfaces of Au/Cu multilayers deposited by magnetron sputtering. The extent of formation of this novel alloy phase depends upon an optimal range of interfacial width primarily governed by the deposition wattage of the direct current magnetron used. Such interfacially confined growth is utilized to grow a ∼300-nm-thick Au/Cu multilayer with thickness of each layer nearly equal to the optimal interfacial width which was obtained from secondary-ion mass spectrometry (SIMS) data. This growth technique is observed to enhance the formation of the novel alloy phase to a considerable extent. The SIMS depth profile also indicates that the mass fragment corresponding to Cu3Au occupies the whole film while x-ray diffraction (XRD) shows almost all the strong peaks belonging to the D023 structure. High-resolution cross-sectional transmission electron microscopy shows the near-perfect growth of the individual layers and also the lattice image of the alloy phase in the interfacial region. Vacuum annealing of the alloy film and XRD studies indicate stabilization of the D023 phase at ∼150 °C. The role of interfacial confinement, the interplay between interfacial strain and free energy, and the hyperthermal species generated during the sputtering process are discussed.

FORMATION OF NOVEL Cu3Au ALLOY PHASE UNDER CONFINEMENT

2005 ◽  
Vol 04 (05n06) ◽  
pp. 1011-1020
Author(s):  
SUBHENDU SARKAR ◽  
ALOKMAY DATTA ◽  
PURUSHOTTAM CHAKRABORTY
Keyword(s):  
Secondary Ion Mass Spectrometry ◽  
Atomic Ratio ◽  
Float Glass ◽  
Alloy Formation ◽  
X Ray Diffraction ◽  
Oriented Growth ◽  
Cross Sectional ◽  
Multilayer Systems ◽  
Transmission Electron ◽  
Interfacial Confinement

Our present work deals with the formation and thermal behavior of a nonbulk alloy phase confined within about 8 nm across the interfaces of Au/Cu multilayer systems. These multilayers deposited on silicon and float glass by DC magnetron sputtering have been studied by secondary ion mass spectrometry (SIMS), X-ray diffraction (XRD) and cross-sectional transmission electron microscopy (XTEM). Along with the highly oriented growth of the Cu and Au layers along [111], Cu 3 Au alloy was found to be present only at the Cu/Au interfaces in the nonbulk tetragonal D023 phase. Co -sputtering of Au and Cu under similar conditions produces only conventional fcc Cu 3 Au alloy phases, suggesting that interfacial confinement plays a significant role in producing the novel Cu 3 Au alloy phase in gold/copper multilayers. This novel phase is found to form only when the interfacial width is less than 10 nm. The D023 alloy phase tends to stabilize, rather than transforming to the bulk L12 phase, when the multilayer is vacuum-annealed at 150°C. As alloy formation spreads out of the interfaces (on vacuum annealing at 200°C), the dominant alloy is CuAu , consistent with the Cu:Au atomic ratio averaged over the multilayer.

Oxidation Kinetics of Cu-Ni Alloy Observed by in situ UHV-TEM

2007 ◽  
Vol 1026 ◽  
Author(s):  
Li Sun ◽  
John E. Pearson ◽  
Judith C. Yang
Keyword(s):  
High Vacuum ◽  
Alloy Film ◽  
Ultra High Vacuum ◽  
Cross Sectional ◽  
Primary Mechanism ◽  
Transmission Electron ◽  
Ni Alloy ◽  
Cu Oxidation ◽  
Kinetics Of

AbstractThe nucleation and growth of Cu2O and NiO islands due to oxidation of Cu-24%Ni(001) films were monitored at various temperatures by in situ ultra-high vacuum (UHV) transmission electron microscopy (TEM). In remarkable contrast to our previous observations of Cu and Cu-Au oxidation, irregular-shaped polycrystalline oxide islands were observed to form with respect to the Cu-Ni alloy film, and an unusual second oxide nucleation stage was noted. Similar to Cu oxidation, the cross-sectional area growth rate of the oxide island is linear indicating oxygen surface diffusion is the primary mechanism of oxide growth.

scholarly journals Posttraumatic Growth and Depreciation from University Students’ Perspectives

2021 ◽  
Author(s):  
Amin Mirzaee ◽  
Azize Alizade ◽  
Behnaz Dowran ◽  
Akram Shafiezadeh
Keyword(s):  
University Students ◽  
Posttraumatic Growth ◽  
Cross Sectional Study ◽  
Cross Sectional ◽  
Cross Cultural Differences ◽  
Present Cross Sectional Study ◽  
Iranian Version ◽  
Posttraumatic Growth Inventory ◽  
The Individual ◽  
Almost All

Objective: This study investigated whether a sample of Iranian university students considered posttraumatic depreciation (PTD) and posttraumatic growth (PTG) as negative or positive. Also, possible gender and religiosity differences in understanding of changes in PTD and PTG were evaluated. Method: The present cross-sectional study was conducted during 2019-2020. The target sample Consisted of 298 students (mean age = 23.79) from 3 Universities in Esfahan and Tehran (Iran), recruited by convenience sampling. The sample answered to the scales, including Posttraumatic Growth Inventory and Posttraumatic Depreciation Inventory; and Iranian version of The Clark and Stark Religious questionnaire. Results: Despite the overall support for the PTG and PTD constructs, the present study showed that there are cross-cultural differences that can affect people's perception of item evaluation positively or negatively. In this study, almost all items that were evaluated differently with operationally defined PTG and PTD belonged to “Relating to Others” factor. The result also displayed gender and religiosity differences in perceptions of growth and depreciation. Conclusion: These results suggest that it is necessary to identify the concept of PTG and PTD in each culture and the individual differences that may affect the perception of PTG and PDT be considered.

Ohmic Contact Formation Mechanism in the Ge/Pd/N-GaAs System

1989 ◽  
Vol 148 ◽  
Author(s):  
E.D. Marshall ◽  
S.S. Lau ◽  
C.J. Palmstrøm ◽  
T. Sands ◽  
C.L. Schwartz ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mass Spectrometry ◽  
Secondary Ion Mass Spectrometry ◽  
Solid Phase ◽  
Cross Sectional ◽  
Ohmic Behavior ◽  
Transmission Electron ◽  
Solid Phase Regrowth ◽  
Ohmic Contact Formation ◽  
Secondary Ion

ABSTRACTAnnealed Ge/Pd/n-GaAs samples utilizing substrates with superlattice marker layers have been analyzed using high resolution backside secondary ion mass spectrometry and cross-sectional transmission electron microscopy. Interfacial compositional and microstructural changes have been correlated with changes in contact resistivity. The onset of good ohmic behavior is correlated with the decomposition of an intermediate epitaxial Pd4(GaAs,Ge2) phase and solid-phase regrowth of Ge-incorporated GaAs followed by growth of a thin Ge epitaxial layer.

scholarly journals Single-cell visualization indicates direct role of sponge host in uptake of dissolved organic matter

2019 ◽  
Vol 286 (1916) ◽  
pp. 20192153 ◽  
Author(s):  
Michelle Achlatis ◽  
Mathieu Pernice ◽  
Kathryn Green ◽  
Jasper M. de Goeij ◽  
Paul Guagliardo ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Secondary Ion Mass Spectrometry ◽  
Physiological Mechanism ◽  
Marine Sponges ◽  
Direct Role ◽  
Transmission Electron ◽  
High Enrichment ◽  
The Individual ◽  
Near Future

Marine sponges are set to become more abundant in many near-future oligotrophic environments, where they play crucial roles in nutrient cycling. Of high importance is their mass turnover of dissolved organic matter (DOM), a heterogeneous mixture that constitutes the largest fraction of organic matter in the ocean and is recycled primarily by bacterial mediation. Little is known, however, about the mechanism that enables sponges to incorporate large quantities of DOM in their nutrition, unlike most other invertebrates. Here, we examine the cellular capacity for direct processing of DOM, and the fate of the processed matter, inside a dinoflagellate-hosting bioeroding sponge that is prominent on Indo-Pacific coral reefs. Integrating transmission electron microscopy with nanoscale secondary ion mass spectrometry, we track 15 N- and 13 C-enriched DOM over time at the individual cell level of an intact sponge holobiont. We show initial high enrichment in the filter-feeding cells of the sponge, providing visual evidence of their capacity to process DOM through pinocytosis without mediation of resident bacteria. Subsequent enrichment of the endosymbiotic dinoflagellates also suggests sharing of host nitrogenous wastes. Our results shed light on the physiological mechanism behind the ecologically important ability of sponges to cycle DOM via the recently described sponge loop.

Domain and Interface Structures of Epitaxial PtSi

1983 ◽  
Vol 25 ◽  
Author(s):  
H. Kawarada ◽  
I. Ohdomari ◽  
S. Horiuchi
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Domain Boundary ◽  
Intermediate Region ◽  
Si Substrate ◽  
Crystalline Perfection ◽  
Lattice Image ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Interface Structures

ABSTRACTThe crystalline perfection of epitaxial PtSi thin films and the microstructure of the PtSi/Si interface have been examined using transmission electron microscopy (TEM), including lattice image techniques. Epitaxial PtSi layers grow with domains which have three different positions on a (111) Si substrate. Inside a domain the crystalline perfection is high, and at the domain boundary no intermediate region has been observed. The undulation of the PtSi/Si interface is larger than that of other epitaxial silicide/Si interfaces. Despite the large undulation, a cross-sectional lattice image shows the epitaxial layer extends to the interface. The interface is abrupt in the epitaxial PtSi/Si system.

MBE Growth of GaAs on Si (100)

1987 ◽  
Vol 91 ◽  
Author(s):  
J. S. Ahearn ◽  
P. Uppal
Keyword(s):  
Secondary Ion Mass Spectrometry ◽  
Tem Analysis ◽  
Cross Sectional ◽  
Mbe Growth ◽  
Si Substrates ◽  
Gaas On Si ◽  
Linear Defects ◽  
Transmission Electron ◽  
Dislocation Densities ◽  
Dislocation Annihilation

ABSTRACTMolecular beam epitaxy (MBE) growth of GaAs on Si was investigated for three Si substrate orientations: exact (100), 4° off (100) towards (011), and 4° off towards (010). Cross-sectional transmission electron microscopy (X-TEM) analysis indicated a high dislocation density at the GaAs-Si interface that decreased away from the interface. Changing the orientation significantly affected the dislocation arrangement in the films.In the exact (100) case, dislocations from different glide systems formed pyramids, and dislocation annihilation resulted in linear defects propagating to the bottom of pits on the GaAs surface. On Si substrates oriented 4° off of (100), dislocation pyramids were not observed which we attribute to the different stresses acting on different glide systems. Planar TEM sections indicated that the dislocation densities at th surfaces of the 2-μm-thick films were 8 × 108 /cm2 for exact (100), 3.4 × 108/cm2 for 4° off (100) towards (010), and 1.6 × 108/cm2 for 4° off towards (011) orientations. When etching was used to evaluate anti-phase domain (APD) density, the exact (100) and off (100) orientations toward (010) showed APD's in some areas; off (100) toward (011) orientations were apparently APD-free. Results of photoluminescence (PL) spectroscopy of each of the wafers showed marked differences in peak intensities for the different orientations. Secondary ion mass spectrometry (SIMS) showed that roughly 1/4 of a monolayer of Si was incorporated in the GaAs, mostly concentrated in the first 250 nm near the GaAs-Si interface.

Crystalline Defects in Silicon Wafer Caused by Prolonged High-Temperature Annealing in Nitrogen Atmosphere

2013 ◽  
Vol 699 ◽  
pp. 445-449
Author(s):  
Haruo Nakazawa ◽  
Masaaki Ogino ◽  
Hideaki Teranishi ◽  
Yoshikazu Takahashi ◽  
Hitoshi Habuka
Keyword(s):  
High Temperature ◽  
Silicon Wafer ◽  
Secondary Ion Mass Spectrometry ◽  
Nitrogen Atmosphere ◽  
Ambient Atmosphere ◽  
High Concentration ◽  
Cross Sectional ◽  
X Ray ◽  
Transmission Electron ◽  
Elemental Analyses

A floating zone (FZ) silicon wafer produced from a Czochralski (CZ) single-crystal ingot was subjected to prolonged annealing at a high temperature. Precipitates were formed in a N2(70%)+O2(30%) ambient atmosphere. The precipitate regions manifested themselves as dark concentric rings in the X-ray topographs. According to the results of cross-sectional transmission electron microscopy observations and energy-dispersive X-ray spectroscopy elemental analyses, nitrogen was distributed throughout the precipitate regions, while oxygen was rich in the periphery of the regions. A high concentration of nitrogen was also directly detected by secondary ion mass spectrometry in the mid-depth of the wafer in the precipitate regions. Electron diffraction analysis of the precipitates showed that their phase was α-Si3N4.

Lattice Structure and Electrical Properties of Epitaxial Aluminum on GaAs

1982 ◽  
Vol 18 ◽  
Author(s):  
Fernando ◽  
A. Ponce ◽  
Stephen J. Eglash
Keyword(s):  
Electron Microscopy ◽  
Lattice Structure ◽  
Epitaxial Relationship ◽  
Cross Sectional ◽  
Barrier Heights ◽  
Transmission Electron ◽  
Current Voltage ◽  
Abrupt Interface ◽  
Crystallographic Planes ◽  
The Individual

The crystal structure of aluminum layers grown by molecular beam epitaxy (MBE) on GaAs(100) was studied using high resolution transmission electron microscopy. We obtained cross-sectional images with nearly atomic resolution of the lattice structure at Al-GaAs interfaces. GaAs epitaxial layers were grown at 585 °C and cooled in the ultrahigh vacuum MBE growth chamber prior to aluminum deposition. After the desired substrate temperature had been achieved, aluminum was immediately deposited onto arsenic-rich surfaces at a rate of 1000 Å h−1.Aluminum layers deposited onto substrates at 80 °C exhibit an Al(110)/GaAs(100) epitaxial relationship along an abrupt interface. In some regions of the interface we observed isolated arsenic crystallites which were epitaxial with the GaAs substrate. The current-voltage (I-V) and capacitance-voltage (C–V) characteristics of this material are well behaved. Barrier heights of 0.79 eV and ideality factors of 1.04 were determined from room temperature I–V measurements.For aluminum deposited onto GaAs substrates at 400 °C, evidence of twodimensional nucleation and growth was observed. The resulting pyramid-shaped aluminum crystallites had facets along crystallographic planes. Two epitaxial relationships were observed: Al(100)/GaAs(100) and Al(110)/GaAs(100). We observed 12 Å steps along the Al(100)–GaAs(100) interface. C–V and scanning electron microscopy measurements indicate that the individual aluminum crystallites are electrically and physically separated.

Epitaxial Growth and Stability of C49 TiSi2 ON Si(111).

1990 ◽  
Vol 198 ◽  
Author(s):  
Hyeongtag Jeon ◽  
J. W. Honeycutt ◽  
C. A. Sukow ◽  
T. P. Humphreys ◽  
R. J. Nemanich ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Diffraction ◽  
Metastable Phase ◽  
Plan View ◽  
Transmission Electron ◽  
Temperature Deposition ◽  
The Individual ◽  
Relationship Of

ABSTRACTEpitaxial TiSi2 films have been grown by molecular beam epitaxy (MBE) on atomically clean Si(111)-orientated substrates. The growth procedure involves the ambient temperature deposition of Ti films of 50Å thickness and annealing to 800°C. In situ low energy electron diffraction (LEED) and Auger electron spectroscopy (AES) techniques have been used to monitor the TiSi2 formation process. The epitaxial films have been identified as the C49 metastable phase by both Raman spectroscopy and electron diffraction. Plan view transmission electron microscopy shows three different connected island morphologies. The individual island structures are single crystal and are grown epitaxially with different crystallographic orientations. The orientational relationship of the largest islands is given by [3 1 1] C49 TiSi2//[112]Si and (130) C49 TiSi2//(l1 1)Si. High resolution transmission electron microscopy (HRTEM) cross-section shows a coherent interface extending over several hundred angstroms.

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