Nanoporous structure of sputter-deposited silicon oxide films characterized by positronium annihilation spectroscopy

“…In Ref. [15] a sample of silica aerogel was used: (b) The Ps formation is measured in a hot Ge crystal. When the Ge crystal is at about 1000 K, all positrons reaching the surface form positronium [29][30][31].…”

Section: Fig 2 Sn(e)−wn(e)mentioning

confidence: 99%

Porosity of Low-κ Materials Studied by Slow Positron Beam

et al. 2005

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“…Nanoscale pores present in porous films have been successfully studied with respect to the conditions of film preparation: deposition time and gas pressure for sputtered silica film [5,9], deposition bias power for PECVD SiOCH--based film [14], film-forming particle size [11], decomposition of porogen [15], composition of precursor solution [10,20,21] and molecular weight of porogen [22] for spin-on-glass MSQ-based films, which illustrates "the great strength" [16] of PAL techniques for evaluating pore dimension.…”

Section: Positronium Annihilation Lifetimementioning

confidence: 99%

“…In the presence of open pores, o-Ps can escape from the film surface into vacuum. Thus the fraction of o-Ps self-annihilation, i.e., I 3γ , determined from the relative fraction of 3γ annihilation with energies lower than 511 keV [5,19], may provide useful information on film porosity. The S parameter defined as the ratio of the integral counts around a small window centered at 511 keV to the total 511 keV annihilation peak counts reflects the annihilation of low-momentum positron-electron (e + −e − ) pairs, whereas the W parameter defined as the ratio of the counts of a wing region in the 2γ photo-peak to the total peak counts reflects the annihilation of high--momentum e + −e − pairs.…”

Section: Introductionmentioning

confidence: 99%

“…Up to date various classes of porous thin films, synthesized as low-k dielectrics [25], high performance gas sensor materials [5], etc., have been studied by PA with variable-energy positron beams. Majority of target films are of silicate or its related derivatives, such as silicon oxide, hydrogen-silsesquioxane (HSQ), methyl-silsesquioxane (MSQ), hexamethyldisiloxane, and trimethylsilane.…”

Section: Introductionmentioning

confidence: 99%

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Variable-Energy Positron Annihilation as Highly Sensitive Nanoporosimetry for Porous Thin Films

Ito

Kobayashi

2005

Acta Phys. Pol. A

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Positron annihilation was applied to measuring critical pore sizes in various materials. In recent years, positron annihilation with a variable-energy positron beam has emerged as a powerful tool for the investigation of porous thin films synthesized as low-k dielectrics, high performance gas sensor materials, and so on. This paper is a brief overview of recent progress in nanopore characterization of thin films by means of positron annihilation with a description of several important issues relevant to positron annihilation.

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Effects of Moisture on the Switching Characteristics of Oxide‐Based, Gapless‐Type Atomic Switches

Tsuruoka

Terabe

Hasegawa

et al. 2011

Adv Funct Materials

260

263

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memory applications. [1,2] The basic structure of the devices consists of a simple metal-ion conductor-metal (MIM) cell, in which a conductive ion layer is sandwiched between an electrochemically active metal electrode (usually Cu or Ag) and an inert metal electrode (for example, Pt). Because its operation mechanism is essentially identical to that of an "atomic switch", whose resistance across a nanometer gap is controlled by the formation and annihilation of a metal bridge under electrical bias, [3] we call this MIM structured cell a "gapless-type atomic switch". [4] On the basis of electrochemical deposition and dissolution of metal on an inert foreign substrate, this type of the cell is also referred to as an electrochemical metallization cell (ECM) or a programmable metallization cell. [5,6] In addition to the simple structures, atomic switches have many unique features, such as low ON resistances, high ON/OFF resistance ratios, excellent scalable potential, low power consumption, and ease of operation. [3,7] Among the various materials suitable for application in an atomic switches and ECM including sulfides, [8,9] chalcogenide glasses, [10,11] and polymers, [12] metal oxides are one of the most promising materials because of their high compatibility with the fabrication processes of complementary metaloxide-semiconductor devices. Resistive switching phenomena have been reported for many MIM cells using a thin layer of Ta 2 O 5 , [13] , SiO 2 , [14,15] , WO 3 , [16] , ZrO 2 , [17] , HfO 2 , [18] SrTiO 3 [19] , etc. In these reports, an amorphous or polycrystalline oxide layer was deposited by sputtering or pulsed laser deposition. The fabricated cells exhibited bipolar switching behavior such that they were SET from a high-resistance (OFF) state to a low-resistance (ON) state at positive bias relative to the electrochemically active electrode and RESET from the ON state to the OFF state at negative bias. The switching mechanism and device characteristics, such as retention time and cycle endurance, have been investigated for the respective cells. However, in the reported works, different experimental conditions were used for the fabrication processes as well as for the electrical measurements. Therefore, one cannot make an appropriate comparison between the results for different oxide materials from separate papers. To understand the switching mechanism completely and to control the function of atomic switches, it is important to know how Effects of Moisture on the Switching Characteristics of Oxide-Based, Gapless-Type Atomic SwitchesResistive switching memories based on the formation and dissolution of a metal filament in a simple metal/oxide/metal structure are attractive because of their potential high scalability, low-power consumption, and ease of operation. From the standpoint of the operation mechanism, these types of memory devices are referred to as gapless-type atomic switches or electrochemical metallization cells. It is well known that oxide materials can absorb moisture from the ambient air, ...

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Nanoporous structure of sputter-deposited silicon oxide films characterized by positronium annihilation spectroscopy

Abstract: Electrical properties of silicon nitride films prepared by electron cyclotron resonance assisted sputter deposition

Cited by 53 publications

References 14 publications

Porosity of Low-κ Materials Studied by Slow Positron Beam

Porosity of Low-κ Materials Studied by Slow Positron Beam

Variable-Energy Positron Annihilation as Highly Sensitive Nanoporosimetry for Porous Thin Films

Effects of Moisture on the Switching Characteristics of Oxide‐Based, Gapless‐Type Atomic Switches

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