In-Situ Surface Composition Measurements of CuGaSe2 Thin Films

1997 ◽  
Vol 485 ◽  
Author(s):  
P. Fons ◽  
A. Yamada ◽  
S. Niki ◽  
H. Oyanagi
Keyword(s):  
Surface Segregation ◽  
Surface Composition ◽  
Bulk Composition ◽  
High Sensitivity ◽  
Film Structure ◽  
High Concentration ◽  
Force Microscopy ◽  
Atomic Force ◽  
Voltage Dependent ◽  
Composition Measurements

AbstractTwo CuGaSe2 films were grown by molecular beam epitaxy onto GaAs (001) substrates with varying Cu/Ga flux ratios under Se overpressure conditions. Growth was interrupted at predetermined times and the surface composition was measured using Auger electron spectroscopy after which growth was continued. After growth, the film composition was analyzed using voltage dependent electron microprobe spectroscopy. Film structure and morphology were also analyzed using x-ray diffraction and atomic force microscopy. The film with a Cu/Ga ratio larger than unity showed evidence of surface segregation of a second Cu-rich phase with a Cu/Se composition ratio slightly greater than unity. A second CuGaSe2 film with a Cu/Ga ratio of less than unity showed no change in surface composition with time and was also consistent with bulk composition measurements. Diffraction measurements indicated a high concentration of twins as well as the presence of domains with mixed c and a axes in the Ga-rich film. The Cu-rich films by contrast were single domain and had a narrower mosaics. High sensitivity scans along the [001] reciprocal axis did not exhibit any new peaks not attributable to either the substrate or the CuGaSe2 thin film.

Experimental amplitude and frequency control of a self-excited microcantilever by linear and nonlinear feedback

2021 ◽  
Author(s):  
Eisuke Higuchi ◽  
Hiroshi Yabuno ◽  
Yasuyuki Yamamoto ◽  
Sohei Matsumoto
Keyword(s):  
Steady State ◽  
Frequency Control ◽  
High Sensitivity ◽  
High Viscosity ◽  
Measurement Methods ◽  
Nonlinear Feedback ◽  
Force Microscopy ◽  
Atomic Force ◽  
Excited Oscillation ◽  
Experimental Approaches

Abstract In recent years, measurement methods that use resonators as microcantilevers have attracted attention because of their high sensitivity, high accuracy, and rapid response time. They have been widely utilized in mass sensing, stiffness sensing, and atomic force microscopy (AFM), among other applications. In all these methods, it is essential to accurately detect shifts in the natural frequency of the resonator caused by an external force from a measured object or sample. Experimental approaches based on self-excited oscillation enable the detection of these shifts even when the resonator is immersed in a high-viscosity environment. In the present study, we experimentally and theoretically investigate the nonlinear characteristics of a microcantilever resonator and their control by nonlinear feedback. We show that the steady-state response amplitude and the corresponding response frequency can be controlled by cubic nonlinear velocity feedback and cubic nonlinear displacement feedback, respectively. Furthermore, the amplitude and frequency of the steady-state self-excited oscillation can be controlled separately. These results will expand application of measurement methods that use self-excited resonators.

scholarly journals Machine Learning Prediction of Surface Segregation Energies on Low Index Bimetallic Surfaces

Energies ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2182
Author(s):  
Damilola Ologunagba ◽  
Shyam Kattel
Keyword(s):  
Machine Learning ◽  
Dft Calculations ◽  
Bimetallic Catalysts ◽  
Density Functional ◽  
Surface Segregation ◽  
Surface Composition ◽  
Bulk Composition ◽  
Statistical Machine Learning ◽  
Bimetallic Surfaces ◽  
Computing Platforms

Surface chemical composition of bimetallic catalysts can differ from the bulk composition because of the segregation of the alloy components. Thus, it is very useful to know how the different components are arranged on the surface of catalysts to gain a fundamental understanding of the catalysis occurring on bimetallic surfaces. First-principles density functional theory (DFT) calculations can provide deeper insight into the surface segregation behavior and help understand the surface composition on bimetallic surfaces. However, the DFT calculations are computationally demanding and require large computing platforms. In this regard, statistical/machine learning methods provide a quick and alternative approach to study materials properties. Here, we trained previously reported surface segregation energies on low index surfaces of bimetallic catalysts using various linear and non-linear statistical methods to find a correlation between surface segregation energies and elemental properties. The results revealed that the surface segregation energies on low index bimetallic surfaces can be predicted using fundamental elemental properties.

Surface segregation of boron in BxGa1−xAs/GaAs epilayers studied by x-ray photoelectron spectroscopy and atomic force microscopy

2003 ◽  
Vol 82 (12) ◽  
pp. 1830-1832 ◽  
Author(s):  
H. Dumont ◽  
D. Rutzinger ◽  
C. Vincent ◽  
J. Dazord ◽  
Y. Monteil ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Photoelectron Spectroscopy ◽  
Surface Segregation ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force

scholarly journals Mechanism of improvement of TiN-coated tool life by nitrogen implantation

2001 ◽  
Vol 16 (11) ◽  
pp. 3293-3303 ◽  
Author(s):  
S. J. Bull ◽  
Yu. P. Sharkeev ◽  
S. V. Fortuna ◽  
I. A. Shulepov ◽  
A. J. Perry
Keyword(s):  
Ion Implantation ◽  
Surface Composition ◽  
Slight Reduction ◽  
Nitrogen Implantation ◽  
Force Microscopy ◽  
Tin Coatings ◽  
Coated Tools ◽  
Atomic Force ◽  
Transmission Electron ◽  
Coated Tool

The life of TiN-coated tools can be improved by a post-coating ion implantation treatment, but the mechanism by which this occurs is still not clear. Nitrogen implantation of both physical-vapor-deposited TiN and CVD TiN leads to surface softening as the dose increases, which has been attributed to amorphization. In this study a combination of transmission electron microscopy and atomic force microscopy was used to characterize the microstructure of implanted TiN coatings on cemented carbide for comparison with mechanical property measurements (nanoindentation, residual stress, etc.), made on the same samples. Ion implantation leads to a slight reduction in the grain size of the TiN in the implanted zone, but there is no evidence for amorphization. Surface softening is observed for physical-vapor-deposited TiN, but this is probably due to a combination of changes in surface composition and the presence of a layer of bubbles generated by the very high implantation doses used.

The effect of carbonization conditions on the properties of rayon-based carbon fibres

1993 ◽  
Vol 5 (2) ◽  
pp. 161-173 ◽  
Author(s):  
David Elmest ◽  
Ken de Vanet
Keyword(s):  
Bulk Composition ◽  
Fibre Surface ◽  
Auger Spectroscopy ◽  
Sodium Content ◽  
Carbonization Temperature ◽  
Carbon Fibres ◽  
Char Residue ◽  
Force Microscopy ◽  
Atomic Force ◽  
Afm Micrographs

The effect of carbonization temperature on the properties of prewoven carbon fibre made from a rayon precursor is examined. Bulk composition is contrasted with surface elemental analysis (XPS) which shows that low carbonization temperatures (2300F, 1260C) produce a fibre with up to 15 and 5 at.% of oxygen and sodium respectively on the surface. At higher firing temperatures (up to 3000, 1649 C), the surface O and Na levels are significantly reduced and the measured fibre surface area declines from 50 m2 g-1 to under 5 ml g-'. Atomic force microscopy (AFM) was used to examine the surface detail of fibres at magnifications over 250000 times. AFM micrographs reveal that the fibre surface after carbonization at low temperatures is covered with a crust believed to be the char residue from tars released during the precarbonization stage. Surface analysis by Auger spectroscopy has confirmed the high oxygen and sodium content of the char material. Use of higher carbonization temperatures results in fibre surface properties which are generally regarded as preferable for use in ablative applications.

Measurement of Interactions between Abrasive Silica Particles and Copper, Titanium, Tungsten and Tantalum

2007 ◽  
Vol 991 ◽  
Author(s):  
Ruslan Burtovyy ◽  
Alex Tregub ◽  
Mansour Moinpour ◽  
Mark Buehler ◽  
Igor Luzinov
Keyword(s):  
Ph Value ◽  
High Sensitivity ◽  
Model Systems ◽  
Thin Polymer Film ◽  
Colloidal Probe ◽  
Force Microscopy ◽  
Atomic Force ◽  
Afm Cantilever ◽  
The Moment ◽  
Silica Slurry

ABSTRACTColloidal probe technique has been widely employed to measure the adhesion between micro- and nanosize objects using atomic force microscopy (AFM). However, majority of studies concerns model systems, which do not incorporate real abrasive particles. The approach applied allows measuring adhesion between real CMP nanoparticles and different surfaces. Thin polymer film with high affinity to the particles was used to anchor the particles to a surface. Hollow glass bead (20-30 μm) representing flat surface was attached to soft AFM cantilever. Application of large hollow bead and the cantilever with small spring constant allows measuring the interactions with high sensitivity. Titanium, tungsten and tantalum metals were sputtered on the bead surface. The effect of different factors such as pH value, concentration and type of a surfactant on adhesion between surfaces of metals and silica slurry has been studied. Character and intensity of interactions at the moment of contact have been evaluated from experimental force-distance curves.

Thermal Stability and Analysis of Laser Deposited Platinum Films

2000 ◽  
Vol 624 ◽  
Author(s):  
G.J. Berry ◽  
J.A. Cairns ◽  
M.R. Davidson ◽  
Y.C. Fan ◽  
A.G. Fitzgerald ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Photoelectron Spectroscopy ◽  
Elevated Temperatures ◽  
Surface Composition ◽  
Direct Write ◽  
Force Microscopy ◽  
Annealing Conditions ◽  
Atomic Force ◽  
Transmission Electron ◽  
Induced Decomposition

ABSTRACTAs the trend towards device miniaturisation continues, surface effects and the thermal stability of metal deposits becomes increasingly important. We present here a study of the morphology and composition of platinum films, produced by the UV-induced decomposition of organometallic materials, under various annealing conditions. The surface composition of the metal deposits was studied by X-ray photoelectron spectroscopy, both as-deposited and following thermal treatment. In addition, the morphology of the surface was studied by atomic force microscopy which enabled the investigation of film restructuring. These studies were performed over a range of temperatures up to 1000°C in air and up to 600°C in reducing environments. Complementary information regarding the film morphology has been obtained from transmission electron microscopy. The data has been used to provide an insight into the effects of elevated temperatures on metal films deposited by a direct write method

Morphology and Dielectric Properties of Reactively Sputtered Aluminum Nitride Thin Films

1996 ◽  
Vol 449 ◽  
Author(s):  
A. G. Randolph ◽  
S.K. Kurinec
Keyword(s):  
Thin Films ◽  
Aluminum Nitride ◽  
Dielectric Strength ◽  
Film Structure ◽  
Force Microscopy ◽  
Atomic Force ◽  
Anion Vacancies ◽  
Lossy Dielectrics ◽  
Auger Electron Spectroscopic Analysis ◽  
Microscopy Examination

ABSTRACTAluminum nitride thin films (∼ 100 mn) have been deposited on silicon substrate by reactive sputtering using Al target in 1:1 Ar:N2 environment. The atomic force microscopy examination revealed continuous microcrystalline film structure. The Auger electron spectroscopic analysis show the presence of oxygen in the films. The annealing at 850 C in nitrogen is found to cause recrystallization and further oxidation of the films. The films can be characterized as lossy dielectrics with relative permittivity ∼ 10, higher than the bulk value of 8.9. Annealing the films is found to reduce anion vacancies and improve the dielectric strength within a range of a few MV/cm in these thin films.

FORCE-DETECTED SCANNED PROBE MAGNETIC RESONANCE MICROSCOPY

2002 ◽  
Vol 16 (20n22) ◽  
pp. 3378-3378
Author(s):  
P. C. HAMMEL
Keyword(s):  
Magnetic Resonance ◽  
Three Dimensional ◽  
High Sensitivity ◽  
Atomic Scale ◽  
Magnetic Resonance Force Microscopy ◽  
Force Microscopy ◽  
Atomic Force ◽  
Unique Method ◽  
Magnetic Resonance Imaging Mri ◽  
Non Destructive

Magnetic Resonance Force Microscopy (MRFM) is a novel scanned probe technique that combines the three-dimensional imaging capabilities of magnetic resonance imaging (MRI) with the high sensitivity and resolution of atomic force microscopy (AFM). This emerging technology holds clear potential for resolution at the atomic scale. When fully realized, MRFM will provide a unique method for non-destructive, chemically specifc, subsurface imaging with applicability to a wide variety of materials. I will review results to date spanning applications of MRFM to nuclear spin, electron spin, and ferromagnetic resonance. I will outline the MRFM technique, discuss its present status and indicate future directions of our effort.

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