Dielectric media based on isolated metallic nanostructures

Kempa, Thomas J.; Carnahan, David; Olek, M.; Correa, Margarita; Giersig, Michael; Cross, Michael; Benham, G.; Sennett, Michael; Ren, Zhifeng; Kempa, Krzysztof

doi:10.1063/1.1996836

Cited by 29 publications

(20 citation statements)

References 15 publications

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“…8 Various conductive fillers like metal particles, conjugated polymers, or carbon black have been used for percolative composites with polymers as matrix materials. [9][10][11][12][13] However, although the reported e9 values were high, the blended materials showed high dielectric loss due to agglomeration of the fillers leading to conductive pathways. Several approaches were used to overcome this limitation.…”

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confidence: 91%

Dielectric properties of silver nanoparticles coated with silica shells of different thicknesses

et al. 2013

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a Core/shell nanoparticles having metallic silver nanoparticle cores of y38 nm in diameter and silica shells of different thicknesses ranging from y3.6-20 nm were prepared. For the silica coating, a slightly modified Stöber method was used which allowed preparing grams of core/shell nanoparticles for the first time. The particles were characterized by UV-vis spectroscopy, dynamic light scattering, scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray scattering. Their dielectric properties were measured as pellets in parallel-plate capacitors. It was found that the permittivity is much influenced by the silica shell thickness with an increase in permittivity for thinner shells. A shell thickness of 20 ¡ 2 nm allowed fabrication of capacitors which have similar characteristics to those of silica, thus, there is no influence of the metal core on the dielectric properties anymore. However, by decreasing the silica shell to 17 ¡ 2, 8 ¡ 1.5, and 6.6 ¡ 1.5 nm the permittivity at high frequencies is increasing from 10, 34, to 41, respectively. The insulator to metal transition was observed for a silica shell thickness of 3.6 ¡ 1 nm.Functionalization of the silica surface with a hydrophobic coating removes surface adsorbed water as observed by the flat dielectric permittivity over a large frequency domain.

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confidence: 91%

Dielectric properties of silver nanoparticles coated with silica shells of different thicknesses

et al. 2013

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“…The Ag-np dipole moments can follow the changes in an adequately low frequency small signal. 5 However, when the small signal frequency approaches the dipole relaxation frequency this ability decreases ͑typically occurring in the microwave region͒. We believe that dipole polarization is the primary permittivity enhancing mechanism in this nanocomposite system, particularly with regards to the smaller Ag-nps below the conduction threshold of silver.…”

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confidence: 99%

“…Each nanoparticle dipole is recognized as behaving like a basic harmonic oscillator or dipole with a relaxation frequency. 5 The deposition of semiconductor device grade films of Al 2 O 3 and HfO 2 on Si is well established. 6,7 However, prior work on using noble metal nanoparticles to increase dielectric constants has focused primarily on polymer and glass dielectrics and processes that are not readily compatible with current integrated circuit fabrication.…”

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confidence: 99%

Permittivity enhancement of aluminum oxide thin films with the addition of silver nanoparticles

Ravindran

Gangopadhyay

et al. 2006

Applied Physics Letters

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Multilayer reactive electron-beam evaporation of thin aluminum oxide layers with embedded silver nanoparticles ͑Ag-nps͒ has been used to create a dielectric thin film with an enhanced permittivity. The results show a frequency dependent increase of the dielectric constant . Overall stack of the control sample was found to be 7.7-7.4 in the 1 kHz-1 MHz range. This is in comparison with = 16.7-13.0 over the same frequency range in the sample with Ag-nps. ideally suited for use with n-and p-type Si over a range of doping levels. The drawback is that the intermediate dielectric constant of Al 2 O 3 limits the capacitance density compared with other high-dielectrics. It is worth noting at this point that the permittivity of metal nanoparticles has been theorized to be superior to that predicted by the classical electrostatic model. 4 This is explained considering the dipole behavior of nonspherical nanoparticles dispersed in a medium. Each nanoparticle dipole is recognized as behaving like a basic harmonic oscillator or dipole with a relaxation frequency. 5 The deposition of semiconductor device grade films of Al 2 O 3 and HfO 2 on Si is well established. 6,7 However, prior work on using noble metal nanoparticles to increase dielectric constants has focused primarily on polymer and glass dielectrics and processes that are not readily compatible with current integrated circuit fabrication. [8][9][10] Conversely, studies utilizing techniques similar to that used here have not focused explicitly on permittivity enhancement or dielectric properties. 11 The primary differences between the work presented here and earlier works on permittivity enhancement with nanoparticles are the manner in which the silver nanoparticles ͑Ag-nps͒ are deposited, the dielectric medium into which they dispersed, and the deposition and characterization of the film on Si substrates.A control set without Ag-nps and an experimental set with Ag-nps were fabricated. In each set, samples were prepared on both p-and p + -Si ͑100͒ with resistivities of 1-10 and 0.0030-0.00 70 ⍀ cm, respectively. The Si substrates were first cleaned with a modified Shiraki process to remove the native oxide and provide a clean, hydrogen passivated surface. 12,13 After drying under nitrogen, they were immediately transferred to a Kurt J. Lesker AXXIS e-beam evaporation system. From a base pressure of 5 ϫ 10 −7 torr, the substrates were heated to 50°C and oxygen was introduced at 5 SCCM ͑SCCM denotes cubic centimeter per minute at STP͒ and 5 ϫ 10 −5 torr. For control samples without silver, 8.73± 0.08 nm of Al 2 O 3 was then evaporated at 0.5 Å / s. For samples with incorporated Ag-nps, Al 2 O 3 , approximately 3 nm in thickness, was deposited and the chamber was again pumped down to 5 ϫ 10 −7 torr. An ultrathin layer of Ag-nps, about half a nanometer in nominal thickness, was deposited under high vacuum. Oxygen was reintroduced, and approximately 3 nm of Al 2 O 3 was again evaporated. This process was repeated until the film consisted of three layers of Al 2 O 3 with tw...

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“…[7,8] Cell adhesion and patterning, bio-electrochemical sensing, and antimicrobial materials combine specific metal nanoparticle properties with the bio-compatible nature of polymers, leading to advanced bio-functional materials. [9][10][11] The choice of polymer thus plays an important role in determining the functionality of the nanocomposite.…”

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confidence: 99%

A Simple Water‐Based Synthesis of Au Nanoparticle/PDMS Composites for Water Purification and Targeted Drug Release

Scott

Gupta

Kulkarni

2010

Macro Chemistry & Physics

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AuNP/PDMS nanocomposites have been synthesized in the form of gels, foams, and films with distinctive structure and morphology. A simple in situ process in aqueous medium for the formation of such composite materials is described. The nanoparticles are held firmly within the PDMS while still being chemically accessible to substances soluble in PDMS. We demonstrate the utility of this property for water purification applications such as removing aromatic solvents and sulfur‐containing contaminants from water. The contaminants can be freed from the composite with a simple thermal treatment, allowing the material to be reused. We also demonstrate chemically selective uptake and release of a fluorescent dye by the nanocomposite as a drug delivery model system.magnified image

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Dielectric media based on isolated metallic nanostructures

Cited by 29 publications

References 15 publications

Dielectric properties of silver nanoparticles coated with silica shells of different thicknesses

Dielectric properties of silver nanoparticles coated with silica shells of different thicknesses

Permittivity enhancement of aluminum oxide thin films with the addition of silver nanoparticles

A Simple Water‐Based Synthesis of Au Nanoparticle/PDMS Composites for Water Purification and Targeted Drug Release

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