The National University of Singapore high energy ion nano-probe facility: Performance tests

Watt, F.; Kan, J.A. van; Rajta, I.; Bettiol, A.A.; Choo, T.F.; Breese, Mark B. H.; Osipowicz, T.

doi:10.1016/s0168-583x(03)01003-6

Cited by 165 publications

(60 citation statements)

References 7 publications

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“…First, a highly focused beam of protons of 250 keV is irradiated into 0.7 Ω.cm resistivity (100) p-type silicon with a beam current of about 10 pA and a spot size of ~ 200 nm. This was carried out using a nuclear microprobe facility at the National University of Singapore [10]. The waveguide structure was written by translating the Inchworm stage on which the sample has been mounted.…”

Section: Methodsmentioning

confidence: 99%

Three-dimensional control of optical waveguide fabrication in silicon

Teo¹,

Bettiol²,

Breese³

et al. 2008

Opt. Express

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Abstract:In this paper, we report a direct-write technique for threedimensional control of waveguide fabrication in silicon. Here, a focused beam of 250 keV protons is used to selectively slow down the rate of porous silicon formation during subsequent anodization, producing a silicon core surrounded by porous silicon cladding. The etch rate is found to depend on the irradiated dose, increasing the size of the core from 2.5 μm to 3.5 μm in width, and from 1.5 μm to 2.6 μm in height by increasing the dose by an order of magnitude. This ability to accurately control the waveguide profile with the ion dose at high spatial resolution provides a means of producing three-dimensional silicon waveguide tapers. Propagation losses of 6.7 dB/cm for TE and 6.8 dB/cm for TM polarization were measured in linear waveguides at the wavelength of 1550 nm.

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Section: Methodsmentioning

confidence: 99%

Three-dimensional control of optical waveguide fabrication in silicon

Teo¹,

Bettiol²,

Breese³

et al. 2008

Opt. Express

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“…The factors λ c /σ b and γ −1 ∂ ζ f i /∂θ sc are Lorentz invariant separately, and for protons the former is of the order of 10 −10 for moderately relativistic beams focused in a spot of ∼ 1 µm and of the order of 10 −8 for protons with p ≈ 2 MeV and focused to σ b 10 nm [69,70]. The estimate (5.11), however, is inapplicable for such non-relativistic particles.…”

Section: Jhep03(2017)049mentioning

confidence: 99%

Scattering of wave packets with phases

Karlovets

2017

J. High Energ. Phys.

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A general problem of 2 → N f scattering is addressed with all the states being wave packets with arbitrary phases. Depending on these phases, one deals with coherent states in (3 + 1) D, vortex particles with orbital angular momentum, the Airy beams, and their generalizations. A method is developed in which a number of events represents a functional of the Wigner functions of such states. Using width of a packet σ p / p as a small parameter, the Wigner functions, the number of events, and a cross section are represented as power series in this parameter, the first non-vanishing corrections to their plane-wave expressions are derived, and generalizations for beams are made. Although in this regime the Wigner functions turn out to be everywhere positive, the cross section develops new specifically quantum features, inaccessible in the plane-wave approximation. Among them is dependence on an impact parameter between the beams, on phases of the incoming states, and on a phase of the scattering amplitude. A model-independent analysis of these effects is made. Two ways of measuring how a Coulomb phase and a hadronic one change with a transferred momentum t are discussed.

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“…[6,7]) and several groups are working on the design of the next generation of quadrupole focusing systems (e.g. [8][9][10]), often involving high demagnification multiple stage lenses.…”

Section: Focusing Mev Ions To Sub-micron Dimensionsmentioning

confidence: 99%

Materials Patterning and Characterisation at the Nanometre Scale Using Focused MeV Ion Beams: Present Achievements and Future Prospects

Grime

2009

Acta Phys. Pol. A

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A key phenomenon in the interaction of MeV ions and solids is that the energy transferred from the primary ions to the target electrons is high compared with atomic and molecular binding energies, but low compared with the ion energy. This means that there is a high probability of modifying the chemical properties of the material (for patterning) or of inducing the emission of electromagnetic radiation (for analysis), yet the path of particle is changed by a negligible amount, which means that focused beams remain sharp even after penetrating long depths into the material. Developments in focusing MeV ions in recent years have pushed the useable beam diameters into the sub-micrometre region, which means that nuclear microbeams are poised to make an impact in both direct write fabrication and micro-analysis at length scales of interest in nanotechnology or microbiology. This paper reviews the science and technology underlying the use of nuclear microbeams (ion solid interactions, focusing systems) and reports on the present status and trends of applications in sub-micron scale applications. Interactions between MeV ions and atoms: the key advantage of MeV ions in nanoscale applicationsMeV ions interact with the atoms of target materials through electrostatic forces between the charged electrons and nuclei of the atoms. Apart from a small fraction of ions which undergo large angle scattering resulting from a close approach to the nucleus (the Rutherford scattering), the primary effect of the interaction is to create a transient electric dipole excitation of the electron structure of the atom. Kinetic energy is absorbed from the ion and may result in ionisation or promoting one or more of the atomic electrons into excited states.The energy transferred from the ion to the atom depends on many factors, but can range from zero to a few tens of keV. This is large compared with electronic binding energies (especially those of valence electrons), giving a high probability of locally modifying the chemistry of the sample, but small compared with the primary ion energy, so that the ion is not strongly deflected or decelerated, and can undergo many thousands of atomic collisions while following an essentially straight path for a large part of its range. This is the unique advantage of MeV ions for high spatial resolution applications: there is a high probability of creating useful effects in the material, yet the primary ion has a long range and a straight path with low lateral scattering. This is demonstrated in Fig.

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The National University of Singapore high energy ion nano-probe facility: Performance tests

Cited by 165 publications

References 7 publications

Three-dimensional control of optical waveguide fabrication in silicon

Three-dimensional control of optical waveguide fabrication in silicon

Scattering of wave packets with phases

Materials Patterning and Characterisation at the Nanometre Scale Using Focused MeV Ion Beams: Present Achievements and Future Prospects

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