Плавление и электромиграция в тонких пленках хрома

Abstract Chromium films with a thickness of 10–40 nm deposited onto silicon substrates by magnetron sputtering are subjected to the action of electric current induced by the tip of an atomic force microscope (AFM) cantilever in air under regular environmental conditions. The melting process at the nanoscale, electric field-induced migration of material, and the chemical reaction of chromium oxidation that occur in melt craters formed around the region affected by the current are investigated using optical and scanning electron microscopies, AFM, and Raman spectroscopy. The flow of melted material induced by electric current is accompanied by the formation and motion of an array of spherical nanoparticles in the melt crater along its periphery. We propose that the formation of nanodrop array at relatively low current densities can be explained by the chromium oxidation reaction and the surface tension of melted material on the silicon substrate.

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ANNEALING TIME EFFECT ON NANOSTRUCTURED n-ZnO/p-Si HETEROJUNCTION PHOTODETECTOR PERFORMANCE

Surface Review and Letters ◽

10.1142/s0218625x15500274 ◽

2015 ◽

Vol 22 (02) ◽

pp. 1550027 ◽

Cited By ~ 2

Author(s):

NADIR. F. HABUBI ◽

RAID. A. ISMAIL ◽

WALID K. HAMOUDI ◽

HASSAM. R. ABID

Keyword(s):

Annealing Time ◽

Silicon Substrates ◽

X Ray Diffraction ◽

Zno Nps ◽

Force Microscopy ◽

Atomic Force ◽

Junction Type ◽

P Type ◽

Quartz Substrates ◽

Two Peaks

In this work, n- ZnO /p- Si heterojunction photodetectors were prepared by drop casting of ZnO nanoparticles (NPs) on single crystal p-type silicon substrates, followed by (15–60) min; step-annealing at 600∘C. Structural, electrical, and optical properties of the ZnO NPs films deposited on quartz substrates were studied as a function of annealing time. X-ray diffraction studies showed a polycrystalline, hexagonal wurtizte nanostructured ZnO with preferential orientation along the (100) plane. Atomic force microscopy measurements showed an average ZnO grain size within the range of 75.9 nm–99.9 nm with a corresponding root mean square (RMS) surface roughness between 0.51 nm–2.16 nm. Dark and under illumination current–voltage (I–V) characteristics of the n- ZnO /p- Si heterojunction photodetectors showed an improving rectification ratio and a decreasing saturation current at longer annealing time with an ideality factor of 3 obtained at 60 min annealing time. Capacitance–voltage (C–V) characteristics of heterojunctions were investigated in order to estimate the built-in-voltage and junction type. The photodetectors, fabricated at optimum annealing time, exhibited good linearity characteristics. Maximum sensitivity was obtained when ZnO / Si heterojunctions were annealed at 60 min. Two peaks of response, located at 650 nm and 850 nm, were observed with sensitivities of 0.12–0.19 A/W and 0.18–0.39 A/W, respectively. Detectivity of the photodetectors as function of annealing time was estimated.

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Lorentz Contact Resonance Imaging for Atomic Force Microscopes: Probing Mechanical and Thermal Properties on the Nanoscale

Microscopy Today ◽

10.1017/s1551929513000989 ◽

2013 ◽

Vol 21 (6) ◽

pp. 18-24 ◽

Cited By ~ 12

Author(s):

Eoghan Dillon ◽

Kevin Kjoller ◽

Craig Prater

Keyword(s):

Viscoelastic Properties ◽

Contact Stiffness ◽

Mechanical And Thermal Properties ◽

Resonance Modes ◽

Atomic Force ◽

Resonance Frequencies ◽

Other Information ◽

Afm Cantilever ◽

Stiffness And Damping ◽

Contact Resonance

Atomic force microscopy (AFM) has been widely used in both industry and academia for imaging the surface topography of a material with nanoscale resolution. However, often little other information is obtained. Contact resonance AFM (CR-AFM) is a technique that can provide information about the viscoelastic properties of a material in contact with an AFM probe by measuring the contact stiffness between the probe and sample. In CR-AFM, an AFM cantilever is oscillated, and the amplitude and frequency of the resonance modes of the cantilever are monitored. When a probe or sample is oscillated, the tip sample interaction can be approximated as an ideal spring-dashpot system using the Voigt-Kelvin model shown in Figure 1. Contact resonance frequencies of the AFM cantilever will shift depending on the contact stiffness, k, between the tip and sample. The damping effect on the system comes from dissipative tip sample forces such as viscosity and adhesion. Damping, η, is observed in a CR-AFM system by monitoring the amplitude and Q factor of the resonant modes of the cantilever. This contact stiffness and damping information can then be used to obtain information about the viscoelastic properties of the material when fit to an applicable model.

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Multiple regimes of operation in bimodal AFM: understanding the energy of cantilever eigenmodes

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.4.45 ◽

2013 ◽

Vol 4 ◽

pp. 385-393 ◽

Cited By ~ 30

Author(s):

Daniel Kiracofe ◽

Arvind Raman ◽

Dalia Yablon

Keyword(s):

Single Frequency ◽

Force Microscopy ◽

Atomic Force ◽

Afm Imaging ◽

Multiple Regimes ◽

Nanoscale Imaging ◽

Relative Kinetic ◽

Series Of Experiments ◽

Tapping Mode Afm ◽

Afm Cantilever

One of the key goals in atomic force microscopy (AFM) imaging is to enhance material property contrast with high resolution. Bimodal AFM, where two eigenmodes are simultaneously excited, confers significant advantages over conventional single-frequency tapping mode AFM due to its ability to provide contrast between regions with different material properties under gentle imaging conditions. Bimodal AFM traditionally uses the first two eigenmodes of the AFM cantilever. In this work, the authors explore the use of higher eigenmodes in bimodal AFM (e.g., exciting the first and fourth eigenmodes). It is found that such operation leads to interesting contrast reversals compared to traditional bimodal AFM. A series of experiments and numerical simulations shows that the primary cause of the contrast reversals is not the choice of eigenmode itself (e.g., second versus fourth), but rather the relative kinetic energy between the higher eigenmode and the first eigenmode. This leads to the identification of three distinct imaging regimes in bimodal AFM. This result, which is applicable even to traditional bimodal AFM, should allow researchers to choose cantilever and operating parameters in a more rational manner in order to optimize resolution and contrast during nanoscale imaging of materials.

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Influence of the Microstructure and Optical Constants on Plasmonic Properties of Copper Nanolayers

Materials ◽

10.3390/ma14237292 ◽

2021 ◽

Vol 14 (23) ◽

pp. 7292

Author(s):

Tomasz Rerek ◽

Beata Derkowska-Zielinska ◽

Marek Trzcinski ◽

Robert Szczesny ◽

Mieczyslaw K. Naparty ◽

...

Keyword(s):

Surface Plasmon ◽

Photoelectron Spectroscopy ◽

Surface Plasmon Polariton ◽

Optical Constants ◽

Localized Surface Plasmon ◽

Silicon Substrates ◽

X Ray ◽

Force Microscopy ◽

Atomic Force ◽

Plasmon Polariton

Copper layers with thicknesses of 12, 25, and 35 nm were thermally evaporated on silicon substrates (Si(100)) with two different deposition rates 0.5 and 5.0 Å/s. The microstructure of produced coatings was studied using atomic force microscopy (AFM) and powder X-ray diffractometer (XRD). Ellipsometric measurements were used to determine the effective dielectric functions <ε˜> as well as the quality indicators of the localized surface plasmon (LSP) and the surface plasmon polariton (SPP). The composition and purity of the produced films were analysed using X-ray photoelectron spectroscopy (XPS).

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Revealing Silver Effects on Bacterial Cell Structure by Atomic Force and Scanning Electron Microscopies

10.21203/rs.3.rs-547371/v1 ◽

2021 ◽

Author(s):

Reem Tambosi ◽

Jamila Djafari ◽

Sylviane Liotenberg ◽

Soufian Ouchane ◽

Nouari Kebaili

Keyword(s):

Bacterial Cell ◽

Metal Toxicity ◽

Food Industry ◽

Cell Structure ◽

Silver Ions ◽

Electron Microscopies ◽

Atomic Force ◽

Morphology And Structure ◽

Damage Membrane ◽

Photosynthesis And Respiration

Abstract The use of silver (Ag+) as an antimicrobial under different forms and at different scales, appears in numerous applications such as in health care, food industry, clothing, fabrics and disinfectants. Yet, there is still important gaps regarding the complete comprehension of the mechanisms of its actions on bacteria. In a previous work, we demonstrated that, silver and copper severly damage membrane proteins involved in photosynthesis and respiration in bacteria exposed to metal excess. Here, we are presenting complementary data using AFM and SEM microscopies, that reveals (i) the drastic effects of Ag+ ions on the morphology and structure of cell membrane and (ii) the formation of Ag+ aggregates that adhere to the bacterial cell surface in Rubrivivax (R.) gelatinosus . Impacts of Ag+ ions on R. gelatinosus are compared to those on the most commonly studied bacteria (Escherichia (E.) coli and Bacillus (B.) subtilis ), while considering the effect of culture grown media on the modification of silver ions. Altogether, these results reveal other levels and subtle aspects of Ag+ toxicity to be taken into account in understanding the general mechanisms of metal toxicity in bacteria.

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Electrostatic shape control of a charged molecular membrane from ribbon to scroll

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1913632116 ◽

2019 ◽

Vol 116 (44) ◽

pp. 22030-22036 ◽

Cited By ~ 4

Author(s):

Changrui Gao ◽

Sumit Kewalramani ◽

Dulce Maria Valencia ◽

Honghao Li ◽

Joseph M. McCourt ◽

...

Keyword(s):

Shape Control ◽

Electrostatic Interactions ◽

Debye Length ◽

Electron Microscopies ◽

Atomic Force ◽

Length Relationship ◽

Transmission Electron ◽

Nacl Concentration ◽

Large Length ◽

And Control

Bilayers of amphiphiles can organize into spherical vesicles, nanotubes, planar, undulating, and helical nanoribbons, and scroll-like cochleates. These bilayer-related architectures interconvert under suitable conditions. Here, a charged, chiral amphiphile (palmitoyl-lysine, C16-K1) is used to elucidate the pathway for planar nanoribbon to cochleate transition induced by salt (NaCl) concentration. In situ small- and wide-angle X-ray scattering (SAXS/WAXS), atomic force and cryogenic transmission electron microscopies (AFM and cryo-TEM) tracked these transformations over angstrom to micrometer length scales. AFM reveals that the large length (L) to width (W) ratio nanoribbons (L/W > 10) convert to sheets (L/W → 1) before rolling into cochleates. A theoretical model based on electrostatic and surface energies shows that the nanoribbons convert to sheets via a first-order transition, at a critical Debye length, with 2 shallow minima of the order of thermal energy at L/W >> 1 and at L/W = 1. SAXS shows that interbilayer spacing (D) in the cochleates scales linearly with the Debye length, and ranges from 13 to 35 nm for NaCl concentrations from 100 to 5 mM. Theoretical arguments that include electrostatic and elastic energies explain the membrane rolling and the bilayer separation–Debye length relationship. These models suggest that the salt-induced ribbon to cochleate transition should be common to all charged bilayers possessing an intrinsic curvature, which in the present case originates from molecular chirality. Our studies show how electrostatic interactions can be tuned to attain and control cochleate structures, which have potential for encapsulating, and releasing macromolecules in a size-selective manner.

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Early-Stage Growth Mechanism and Synthesis Conditions-Dependent Morphology of Nanocrystalline Bi Films Electrodeposited from Perchlorate Electrolyte

Nanomaterials ◽

10.3390/nano10061245 ◽

2020 ◽

Vol 10 (6) ◽

pp. 1245 ◽

Cited By ~ 2

Author(s):

Daria Tishkevich ◽

Sergey Grabchikov ◽

Tatiana Zubar ◽

Denis Vasin ◽

Sergei Trukhanov ◽

...

Keyword(s):

Growth Mechanism ◽

Early Stage ◽

Abnormal Behavior ◽

Morphological Properties ◽

Synthesis Conditions ◽

Force Microscopy ◽

Atomic Force ◽

Galvanostatic Regime ◽

Current Densities ◽

Deposition Duration

Bi nanocrystalline films were formed from perchlorate electrolyte (PE) on Cu substrate via electrochemical deposition with different duration and current densities. The microstructural, morphological properties, and elemental composition were studied using scanning electron microscopy (SEM), atomic force microscopy (AFM), and energy-dispersive X-ray microanalysis (EDX). The optimal range of current densities for Bi electrodeposition in PE using polarization measurements was demonstrated. For the first time, it was shown and explained why, with a deposition duration of 1 s, co-deposition of Pb and Bi occurs. The correlation between synthesis conditions and chemical composition and microstructure for Bi films was discussed. The analysis of the microstructure evolution revealed the changing mechanism of the films’ growth from pillar-like (for Pb-rich phase) to layered granular form (for Bi) with deposition duration rising. This abnormal behavior is explained by the appearance of a strong Bi growth texture and coalescence effects. The investigations of porosity showed that Bi films have a closely-packed microstructure. The main stages and the growth mechanism of Bi films in the galvanostatic regime in PE with a deposition duration of 1–30 s are proposed.

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Surface of Alumina Films after Prolonged Breakdowns in Galvanostatic Anodization

International Journal of Electrochemistry ◽

10.4061/2011/126726 ◽

2011 ◽

Vol 2011 ◽

pp. 1-5 ◽

Cited By ~ 3

Author(s):

Christian Girginov ◽

Stephan Kozhukharov

Keyword(s):

Surface Roughness ◽

Atomic Force Microscopy ◽

Electrode Surface ◽

Roughness Parameters ◽

Anodic Films ◽

Force Microscopy ◽

Alumina Films ◽

Anodization Time ◽

Atomic Force ◽

Current Densities

Breakdown phenomena are investigated at continuous isothermal (20∘C) and galvanostatic (0.2–5 mA cm−2) anodizing of aluminum in ammonium salicylate in dimethylformamide (1 M AS/DMF) electrolyte. From the kinetic -curves, the breakdown voltage () values are estimated, as well as the frequency and amplitude of oscillations of formation voltage () at different current densities. The surface of the aluminum specimens was studied using atomic force microscopy (AFM). Data on topography and surface roughness parameters of the electrode after electric breakdowns are obtained as a function of anodization time. The electrode surface of anodic films, formed with different current densities until the same charge density has passed (2.5 C cm−2), was assessed. Results are discussed on the basis of perceptions of avalanche mechanism of the breakdown phenomena, due to the injection of electrons and their multiplication in the volume of the film.

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All chemical YBa2Cu3O7 superconducting multilayers: Critical role of CeO2 cap layer flatness

Journal of Materials Research ◽

10.1557/jmr.2009.0160 ◽

2009 ◽

Vol 24 (4) ◽

pp. 1446-1455 ◽

Cited By ~ 59

Author(s):

M. Coll ◽

J. Gàzquez ◽

R. Huhne ◽

B. Holzapfel ◽

Y. Morilla ◽

...

Keyword(s):

Critical Role ◽

High Energy ◽

Buffer Layers ◽

Solution Deposition ◽

Ybco Films ◽

Force Microscopy ◽

Atomic Force ◽

Current Densities ◽

Atomically Flat

New advances toward microstructural improvement of epitaxial CeO2 films grown by chemical solution deposition and their use as buffer layers for YBa2Cu3O7 (YBCO) films are presented. We demonstrate that the degree of epitaxy and the fraction of (001) atomically flat surface area are controlled by the incorporation of tetravalent (Zr4+) or trivalent (Gd3+) cations into the ceria lattice. The degree of epitaxy has been investigated by means of Rutherford backscattering spectroscopy-channeling and reflection high-energy electron diffraction, and a new methodology is also presented to quantify the fraction of (001) atomically flat area from atomic force microscopy images. Results are further correlated with the superconducting properties, microstructure, and texture of YBCO films grown by the trifluoroacetate route. A comparison with pulsed laser deposition and YBCO films grown on the same ceria layers is also presented. This growth procedure has allowed us to obtain all chemical multilayer films with controlled microstructure and critical current densities above 4 MA cm−2 at 77 K.

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Current Dependence of Reversible Electromigration Induced Resistance Changes in Short Al Lines and Interpretation of Irreversible Effects

MRS Proceedings ◽

10.1557/proc-428-121 ◽

1996 ◽

Vol 428 ◽

Cited By ~ 1

Author(s):

A. H. Verbruggen ◽

M. J. C. Van Den Homberg ◽

A. J. Kalkman ◽

J. R. Kraayeveld ◽

A. W.-J. Willemsen ◽

...

Keyword(s):

Atomic Force Microscopy ◽

Induced Resistance ◽

Current Density ◽

Linear Dependence ◽

Resistance Change ◽

Current Dependence ◽

Force Microscopy ◽

Atomic Force ◽

Irreversible Effects ◽

Current Densities

AbstractChanges in the electrical resistance induced by electromigration in short (< 20 μm) Al lines show a rather well-defined behavior. For current densities j below a critical value jc the resistance change saturates with time and the resistance fully recovers when the current is switched off. Above the critical current density the induced resistance changes do not saturate and vary approximately linearly with time. In this case the resistance changes recover only partially after removal of the current. We report (i) measurements of the current dependence of the magnitude of the reversible resistance changes and (ii) the results of atomic force microscopy (AFM) inspection of the lines after stressing with current densities above jc. The resistance measurements were made with a high-resolution AC bridge technique. The samples were pure, unpassivated Al lines with a film thickness of 100 nm and a line width of 2 gm. The results show a linear dependence between the magnitude of the reversible changes and the current density. The linear dependence is predicted by two models. The first is based on a description of the vacancy flux and the second on a description of the build-up of mechanical stress during an electromigration experiment. To study the origin of the irreversible effects, samples were stressed at current densities above jc, and the induced irreversible changes in the resistance were recorded. Both negative and positive changes of the resistance were observed. After six hours the experiment was stopped and the lines were inspected by atomic force microscopy. It was always possible to observe a void, a hillock or a hillock/void pair that was created during the passage of the DC current. Moreover, lines with decreasing resistance during stress always showed a hillock and lines with an increased resistance always showed a void.

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