Focused ion beam and electron microscopy characterization of nanosharp tips and microbumps on silicon and metal thin films formed via localized single-pulse laser irradiation

Moening, Joseph P.; Georgiev, Daniel G.; Lawrence, Joseph G.

doi:10.1063/1.3524367

Cited by 14 publications

(5 citation statements)

References 28 publications

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“…What causes the electrode material to bulge prior to crater formation? Qualitatively similar bumps and craters are observed to form on thin gold films on glass substrates when irradiated with nanosecond laser pulses. − At pulse energies below the ablation level, small hollow bumps are observed to form on the film surface. As the laser pulse energy is increased, the bumps become wider and taller.…”

Section: Discussionmentioning

confidence: 81%

Droplet Conductivity Strongly Influences Bump and Crater Formation on Electrodes during Charge Transfer

2018

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Aqueous droplets acquire charge when they contact electrodes in high voltage electric fields, but the exact mechanism of charge transfer is not understood. Recent work by Elton et al. revealed that electrodes are physically pitted during charge transfer with aqueous droplets. The pits are believed to result when a dielectric breakdown arc occurs as a droplet approaches the electrode and the associated high current density transiently locally melts the electrode, leaving distinct crater-like deformations on the electrode surface. Here we show that the droplet conductivity strongly modulates the pitting morphology but has little effect on the amount of charge transferred. Electron and atomic force microscopy shows that deionized water droplets yield no observable deformations, but as the salt concentration in the droplet increases above 10 M, the deformations become increasingly large. The observed intensity of the flash of light released during the dielectric breakdown arc also increases with droplet conductivity. Surprisingly, despite the large difference in pitting morphology and corresponding arc intensity, droplets of any conductivity acquire similar amounts of charge. These results suggest that the energy transferred during dielectric breakdown is primarily responsible for electrode pitting rather than the total amount of energy released during charge transfer.

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Section: Discussionmentioning

confidence: 81%

Droplet Conductivity Strongly Influences Bump and Crater Formation on Electrodes during Charge Transfer

2018

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“…In metal oxide semiconductors such as NiO x , vacancies, point defects, and interstitials often play a dominant role in determining the electrical, optical, and magnetic properties and such defects can be introduced by controlled excitation of electrons using laser irradiation. So far, laser irradiation has been used for modifying intrinsic properties of metallic , semiconducting , superconducting , multiferroic , and ceramic thin films. In this report, we explored the effect of ultra‐violet (UV) laser irradiation on the properties of nickel oxide thin films (NiO x ), which could be of interest to property tailoring for specific applications.…”

Section: Introductionmentioning

confidence: 99%

Modification of reactively sputtered NiO_xthin films by pulsed UV laser irradiation

Itapu

Georgiev

Uprety

et al. 2016

Phys. Status Solidi A

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This work reports on the effect of ultraviolet (UV) laser irradiation on the structural, electrical, and optical properties of nickel oxide (NiOx) thin films, deposited by reactive sputtering of nickel in an oxygen containing atmosphere. It was found that the conduction type can be changed from p‐type to n‐type and the resistivity decreased as the number of laser pulses is increased and then increases again. The as‐deposited films are polycrystalline, while laser irradiation renders the films amorphous. The observed transition from O‐rich NiOx as‐deposited films to Ni‐rich laser‐irradiated NiOx can be significant to electrochromic, resistive switching, and other applications. The band gap of the as‐deposited and the laser irradiated NiOx films was obtained from spectroscopic ellipsometry measurements and was found to slightly increase upon laser irradiation. It is also observed that the surface roughness increases slightly. Aging effects or instabilities in the structure and composition of the films are also observed under normal conditions.

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“…We note the observed formation of pancake shaped voids in metal films under moderate power density (P ∼ 1 W/µm 2 ) laser beams. 13 Similar nanovoids have been explained by thermal instabilities and recrystallization. 16 The phenomenon of laser ablation 17 is observed for P > ∼ 10 W/µm 2 .…”

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confidence: 77%

Plasmonic mediated nucleation of resonant nano-cavities

Karpov

Nardone

Subashiev

2012

Applied Physics Letters

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We predict plasmonic mediated nucleation of pancake shaped resonant nano-cavities in metallic layers that are penetrable to laser irradiation. The underlying physics is that the cavity provides a narrow plasmonic resonance that maximizes its polarizability in an external field. The resonance yields a significant energy gain making the formation of such cavities highly favorable. Possible implications include nano-optics and generation of the dielectric bits in conductive films that underlie the existing optical recording phase change technology. PACS numbers:Non-photochemical acceleration of nucleation under laser irradiation or static electric fields has been observed in a number of systems. [1][2][3][4] The effect was attributed to electric field induced polarization and lowering of the nucleation barrier. For ac fields, the frequency dependence of the material polarization, especially near plasmonic resonances, has not yet been considered and may completely modify that effect; it is of particular importance for metallic phases.In this letter we predict a phenomenon of plasmonic mediated nucleation of nano-cavities in metallic layers that are penetrable to laser fields. The underlying idea is that the nucleated cavity provides a narrow plasmonic resonance that maximizes its polarizability in an external field. The ability to adjust resonance oscillations frequency and phase makes such cavities highly energetically favorable.Our consideration is based on the classical nucleation theory 5,6 , which accounts for the bulk µV and surface σA contributions to the free energy. With the addition of the term F E to describe the electric polarization gain, the free energy is F = F E + µV + σA, where µ is the difference in chemical potential (per volume) due to cavity nucleation, σ is the surface tension, and V and A are the cavity volume and surface area, respectively. Our analysis below starts with the case of µ < 0, corresponding to a metastable metallic system wherein nucleation is naturally expected. We then consider the case of a stable metal layer, µ > 0, where cavities are energetically unfavorable in zero field.For a static field, the polarization induced energy gain of a particle that nucleates in a dielectric material, with permittivity ǫ, can be represented as, 6where α is the particle polarizability, and E is the field strength. A subtle point here is that ǫ makes Eq. (1) different from the energy of a dipole in an external field; ǫ reflects the contributions from all charges in the system, including those responsible for the field. That factor was confirmed by several authors. [6][7][8] Eq.(1) was originally obtained by integrating, over the entire space, the energy density difference caused by introduction of the particle. It must be modified for the case of dispersive media (metals), in which( 2) where ω is the field frequency, τ is the relaxation time, and ω p = 4πN e 2 /m is the plasma frequency with N being the electron concentration, m the electron mass, and e the electron charge. We assume, as usual, τ...

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Focused ion beam and electron microscopy characterization of nanosharp tips and microbumps on silicon and metal thin films formed via localized single-pulse laser irradiation

Cited by 14 publications

References 28 publications

Droplet Conductivity Strongly Influences Bump and Crater Formation on Electrodes during Charge Transfer

Droplet Conductivity Strongly Influences Bump and Crater Formation on Electrodes during Charge Transfer

Modification of reactively sputtered NiO_xthin films by pulsed UV laser irradiation

Plasmonic mediated nucleation of resonant nano-cavities

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Focused ion beam and electron microscopy characterization of nanosharp tips and microbumps on silicon and metal thin films formed via localized single-pulse laser irradiation

Cited by 14 publications

References 28 publications

Droplet Conductivity Strongly Influences Bump and Crater Formation on Electrodes during Charge Transfer

Droplet Conductivity Strongly Influences Bump and Crater Formation on Electrodes during Charge Transfer

Modification of reactively sputtered NiOxthin films by pulsed UV laser irradiation

Plasmonic mediated nucleation of resonant nano-cavities

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Modification of reactively sputtered NiO_xthin films by pulsed UV laser irradiation