Surface force interactions between micrometer-size polystyrene spheres and silicon substrates using atomic force techniques

The contact radii arising from surface forces were determined for cross-linked polystyrene particles having radii between 1.5 and 10 μm in contact with SiO2/silicon substrates using scanning electron microscopy. It was observed that the contact radius varied approximately as the particle radius to the 0.42 ± 0.13 power. These results are consistent with the theories that assume plastic response of the materials, such as that proposed by Maugis and Pollock [D. Maugis and H. M. Pollock, Acta Metall. 32, 1323 (1984)] but are inconsistent with the predictions of models which assume only elastic response, such as that of Johnson, Kendall, and Roberts [K. L. Johnson, K. Kendall, and A. D. Roberts, Proc. R. Soc. London A 324, 301 (1971)]. The thermodynamic work of adhesion, calculated from the experimental results, was found to be 0.32 J/m2, which is significantly smaller than that reported previously on a similar system.

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Binary Self-Assembly of Nanocolloidal Arrays using Concurrent and Sequential Spin Coating Techniques

Materials ◽

10.3390/ma14020274 ◽

2021 ◽

Vol 14 (2) ◽

pp. 274

Author(s):

Shih-Jyun Shen ◽

Demei Lee ◽

Yu-Chen Wu ◽

Shih-Jung Liu

Keyword(s):

Silicon Substrate ◽

Self Assembly ◽

Spin Coating ◽

Processing Parameters ◽

The Self ◽

Silicon Substrates ◽

Processing Conditions ◽

Polystyrene Spheres ◽

Optimal Processing ◽

Spin Coater

This paper reports the binary colloid assembly of nanospheres using spin coating techniques. Polystyrene spheres with sizes of 900 and 100 nm were assembled on top of silicon substrates utilizing a spin coater. Two different spin coating processes, namely concurrent and sequential coatings, were employed. For the concurrent spin coating, 900 and 100 nm colloidal nanospheres of latex were first mixed and then simultaneously spin coated onto the silicon substrate. On the other hand, the sequential coating process first created a monolayer of a 900 nm nanosphere array on the silicon substrate, followed by the spin coating of another layer of a 100 nm colloidal array on top of the 900 nm array. The influence of the processing parameters, including the type of surfactant, spin speed, and spin time, on the self-assembly of the binary colloidal array were explored. The empirical outcomes show that by employing the optimal processing conditions, binary colloidal arrays can be achieved by both the concurrent and sequential spin coating processes.

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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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Heat Transfer Spectroscopy and “Heat Transfer-Distance” Curves

Volume 13: Nano-Manufacturing Technology; and Micro and Nano Systems, Parts A and B ◽

10.1115/imece2008-69231 ◽

2008 ◽

Author(s):

Arvind Narayanaswamy ◽

Sheng Shen ◽

Gang Chen

Keyword(s):

Heat Transfer ◽

Radiative Transfer ◽

Atomic Force Microscope ◽

Near Field ◽

Surface Force ◽

Casimir Forces ◽

Distance Curve ◽

Transfer Distance ◽

Atomic Force ◽

Order Of Magnitude

Thermal radiative transfer between objects as well as near-field forces such as van der Waals or Casimir forces have their origins in the fluctuations of the electrodynamic field. Near-field radiative transfer between two objects can be enhanced by a few order of magnitude compared to the far-field radiative transfer that can be described by Planck’s theory of blackbody radiation and Kirchoff’s laws. Despite this common origin, experimental techniques of measuring near-field forces (using the surface force apparatus and the atomic force microscope) are more sophisticated than techniques of measuring near-field radiative transfer. In this work, we present an ultra-sensitive experimental technique of measuring near-field using a bi-material atomic force microscope cantilever as the thermal sensor. Just as measurements of near-field forces results in a “force distance curve”, measurement of near-field radiative transfer results in a “heat transfer-distance” curve. Results from the measurement of near-field radiative transfer will be presented.

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Surface Force Tensile Interactions Between Micrometer Size Particles and a Polyester-PDMS Block Copolymer Substrate

Particles On Surfaces ◽

10.1201/9781003067429-2 ◽

2020 ◽

pp. 33-46

Author(s):

Lawrence P. DeMejo ◽

D. S. Rimai ◽

Jiann H. Chen ◽

Ray Bowen

Keyword(s):

Block Copolymer ◽

Surface Force ◽

Micrometer Size

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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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Anomalous Interfacial Structuring of a Non-Halogenated Ionic Liquid: Effect of Substrate and Temperature

Colloids and Interfaces ◽

10.3390/colloids2040060 ◽

2018 ◽

Vol 2 (4) ◽

pp. 60 ◽

Cited By ~ 5

Author(s):

Milad Radiom ◽

Patricia Pedraz ◽

Georgia Pilkington ◽

Patrick Rohlmann ◽

Sergei Glavatskih ◽

...

Keyword(s):

Ionic Liquid ◽

Surface Charge ◽

Force Measurement ◽

Surface Force ◽

Solid Surfaces ◽

Effect Of Temperature ◽

Decay Length ◽

Force Microscopy ◽

Large Size ◽

Atomic Force

We investigate the interfacial properties of the non-halogenated ionic liquid (IL), trihexyl(tetradecyl)phosphonium bis(mandelato)borate, [P6,6,6,14][BMB], in proximity to solid surfaces, by means of surface force measurement. The system consists of sharp atomic force microscopy (AFM) tips interacting with solid surfaces of mica, silica, and gold. We find that the force response has a monotonic form, from which a characteristic steric decay length can be extracted. The decay length is comparable with the size of the ions, suggesting that a layer is formed on the surface, but that it is diffuse. The long alkyl chains of the cation, the large size of the anion, as well as crowding of the cations at the surface of negatively charged mica, are all factors which are likely to oppose the interfacial stratification which has, hitherto, been considered a characteristic of ionic liquids. The variation in the decay length also reveals differences in the layer composition at different surfaces, which can be related to their surface charge. This, in turn, allows the conclusion that silica has a low surface charge in this aprotic ionic liquid. Furthermore, the effect of temperature has been investigated. Elevating the temperature to 40 °C causes negligible changes in the interaction. At 80 °C and 120 °C, we observe a layering artefact which precludes further analysis, and we present the underlying instrumental origin of this rather universal artefact.

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Growth Front Roughening of Room Temperature Deposited Oligomer Thin Films

MRS Proceedings ◽

10.1557/proc-648-p6.20 ◽

2000 ◽

Vol 648 ◽

Author(s):

D. Tsamouras ◽

G. Palasantzas ◽

J. Th. M. De Hosson ◽

G. Hadziioannou

Keyword(s):

Thin Films ◽

Film Thickness ◽

Room Temperature ◽

Growth Front ◽

Silicon Substrates ◽

Height Distribution ◽

Force Microscopy ◽

Atomic Force ◽

Roughness Amplitude ◽

Non Gaussian

AbstractGrowth front scaling aspects are investigated for PPV-type oligomer thin films vapor- deposited onto silicon substrates at room temperature. For film thickness d~15-300 nm, commonly used in optoelectronic devices, correlation function measurement by atomic force microscopy yields roughness exponents in the range H=0.45±0.04, and an rms roughness amplitude which evolves with film thickness as a power law σ∝ dβ with β=0.28±0.05. The non-Gaussian height distribution and the measured scaling exponents (H and β) suggest a roughening mechanism close to that described by the Kardar-Parisi-Zhang scenario.

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