Charge Equilibration Time of Slow, Highly Charged Ions in Solids

Hattass, M.; Schenkel, T.; Hamza, A. V.; Barnes, A. V.; Newman, M. W.; McDonald, J.; Niedermayr, Thomas; Machicoane, G.; Schneider, Dieter

doi:10.1103/physrevlett.82.4795

Cited by 79 publications

(48 citation statements)

References 32 publications

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“…This value is of the same order as the typical excitation times for an electron-hole pair of eV separation as well as the response time of the electron gas to screen the projectile. Very recently, Hattass et al [20] have found comparably short charge equilibration times (7 fs) for, e.g., Th 651 penetrating 5 nm C foils. Shorter interaction times are crucial to study effects which are present in the preequilibrium range only: Juaristi et al [21] investigated the dependence of the electronic stopping on projectile L-and K-shell vacancies on a 10 fs time scale.…”

Section: Kvi Atomic Physics Rijksuniversiteit Groningen Zernikelaanmentioning

confidence: 98%

ZOscillations in Ion-Induced Fullerene Fragmentation

et al. 2000

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Section: Kvi Atomic Physics Rijksuniversiteit Groningen Zernikelaanmentioning

confidence: 98%

ZOscillations in Ion-Induced Fullerene Fragmentation

et al. 2000

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“…We note that these chemical methods can also be employed while target ionization is maximized. Highly charged ions with keV energies deposit their potential energy (the sum of the binding energies of the electrons that were removed when forming the ion) within about 10 fs, close to the target surface [15]. This fast charge equilibration constitutes an energy deposition rate matched only by MeV/u heavy ions, or heavy clusters with MeV energies.…”

Section: Interaction Of Highly Charged Ions With Solidsmentioning

confidence: 99%

<title>Highly charged ion-secondary ion mass spectrometry (HCI-SIMS): toward metrology solutions for sub-100-nm technology nodes</title>

et al. 2001

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The transition to semiconductor design nodes below 100 nm will create high demands on metrology solutions for the detection and chemical characterization of defects and particles throughout all processing steps. The compositional analysis of particles with sizes below about 20 nm is one particular challenge. We describe progress in the development of a highly charged ion based secondary ion mass spectrometry (HCI-SIMS) schemes aimed at addressing this challenge. Using ions like Xe 48+ as projectiles increases secondary ion yields by several orders of magnitude and enables the application of coincidence counting techniques for the characterization of nano-environments of selected species. Additionally, an ion emission microscope was developed for defect imaging and we report examples of its application. We discuss steps of combining beam focusing, coincidence analysis and emission microscopy to enable compositional analysis of sub 20 nm size particles. IntroductionThe analysis of surfaces and semiconductor structures faces the problem of increasing demands on lateral resolution and detection sensitivity. According to the International Technology Roadmap for Semiconductors, the detection and chemical characterization of particles with diameters of less than 20 nm will become important for technology nodes below 100 nm, which are currently anticipated for 2005 [1]. It is interesting to note that the need for chemical analysis of these small particles coincides with a new analytical challenges in nanoscience were nanocrystals with comparable dimensions are investigated for their unique properties [2]. Scanning electron microscopy (SEM) in combination with EDX (energy dispersive x-ray spectroscopy) or AES (Auger electron spectroscopy) have advanced the field of defect and particle characterization to amazing levels of lateral resolution (few nm) with high (~0.1 %) detection sensitivities. Scanning probe techniques such as atomic force microscopy (AFM) are nondestructive and can deliver topographical information on an even smaller length scale, down to atomic resolution in special applications. However, AFM generally does not deliver information on the chemical composition of particles. The latter is crucial for the pinpointing of contamination sources [3].Elemental composition and chemical structure of surfaces can be probed by static secondary ion mass spectrometry, most widely in time-of-flight mode (TOF-SIMS). TOF-SIMS allows the imaging of the top monolayers of surfaces with a few hundred nm resolution and can detect secondary ions over the full mass range (up to a few thousand amu) in parallel. The lateral resolution in adaptations of focused ion beam systems with SIMS allows imaging of the elemental composition of samples with 10 to 30 nm

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“…In contrast, the high density of electrons in antibonding states created by an intense, ultra-fast electronic excitation can impart an impulse leading to atomic displacements [9][10][11][12]. Direct evidence of atomic motion on a ∼160-fs time scale due to antibonding state excitation is reported by Petek et al [13].The deposition of potential energy from slow, highly charged ions (SHCI) such as Xe 44+ (616-keV kinetic energy in this study) in semiconductor surfaces forms highly localized regions of intense electronic excitation [10,14] on femtosecond time scales [15]. We define slow ions as ions with velocities less than the Bohr velocity.…”

mentioning

confidence: 90%

“…The deposition of potential energy from slow, highly charged ions (SHCI) such as Xe 44+ (616-keV kinetic energy in this study) in semiconductor surfaces forms highly localized regions of intense electronic excitation [10,14] on femtosecond time scales [15]. We define slow ions as ions with velocities less than the Bohr velocity.…”

Section: Introductionmentioning

confidence: 99%

Exciton dispersion in silicon nanostructures formed by intense, ultra-fast electronic excitation

Hamza

Newman

Thielen

et al. 2003

Applied Physics A: Materials Science & Processing

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The intense, ultra-fast electronic excitation of clean silicon (100)-(2 × 1) surfaces leads to the formation of silicon nanostructures embedded in silicon, which photoluminesce in the yellow-green (∼ 2-eV band gap). The silicon surfaces were irradiated with slow, highly charged ions (e.g. Xe 44+ and Au 53+ ) to produce the ultra-fast electronic excitation. The observation of excitonic features in the luminescence from these nanostructures has recently been reported. In this paper we report the dispersion of the excitonic features with laser excitation energy. A phonon-scattering process is proposed to explain the observed dispersion. Bulk silicon is a poor light emitter owing to its indirect band gap. Since 1990 many authors have observed visible-light emission from silicon nanostructures. Two of the prominent examples are porous silicon (e.g. [1,2]) and silicon nanoclusters in silica (e.g. [3]). Visible emission has also been observed from one-dimensionally confined silicon in silicon/SiO 2 superlattices [4]. Many authors show that the visible emission can be due to quantum confinement of the excitation to a structure with less than 5-nm radius (Bohr radius of an exciton in silicon) (e.g. [2]). Confinement leads to a widening of the band gap and increased oscillator strength for the transition (e.g. [5]). The extent of changes (direct versus indirect) in the band structure of nanostructures of silicon is still a controversial topic (e.g. [6,7]).Recently, we have briefly reported the observation of light emission from nanostructures on silicon formed by intense, ultra-fast electronic excitation [8]. The intense, ultra-fast electronic excitation of clean silicon (100)-(2 × 1) surfaces leads to the formation of silicon nanostructures embedded in silicon, which photoluminesce at ∼560-nm wavelength (∼ 2-eV band gap). The silicon surfaces were irradiated with slow, and Au 53+ ) to produce the electronic excitation. The observation of excitonic features in the luminescence is particularly unusual for silicon nanostructures. The temperature dependence of the luminescence and the measurement of the triplet-singlet splitting of the emission strongly support the excitonic assignment. Intense, ultra-fast electronic excitation of a semiconductor surface such as silicon leads to the promotion of many (> 10 3 ) valence (bonding) electrons into the conduction bands (antibonding states). The promotion of a single electron or even many electrons into antibonding states does not impart a sufficient force for a sufficient length of time to cause displacement of the atomic nuclei. In contrast, the high density of electrons in antibonding states created by an intense, ultra-fast electronic excitation can impart an impulse leading to atomic displacements [9][10][11][12]. Direct evidence of atomic motion on a ∼160-fs time scale due to antibonding state excitation is reported by Petek et al. [13].The deposition of potential energy from slow, highly charged ions (SHCI) such as Xe 44+ (616-keV kinetic energy in this study) in se...

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Charge Equilibration Time of Slow, Highly Charged Ions in Solids

Cited by 79 publications

References 32 publications

ZOscillations in Ion-Induced Fullerene Fragmentation

ZOscillations in Ion-Induced Fullerene Fragmentation

<title>Highly charged ion-secondary ion mass spectrometry (HCI-SIMS): toward metrology solutions for sub-100-nm technology nodes</title>

Exciton dispersion in silicon nanostructures formed by intense, ultra-fast electronic excitation

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