Positronium Formed by Recombination of Positron-Electron Pairs in Polymers

Sato, Kosuke; Shanai, D.; Hotani, Yohei; Ougizawa, Toshiaki; Ito, Kenji; Hirata, Koichi; Kobayashi, Yoshinori

doi:10.1103/physrevlett.96.228302

Cited by 64 publications

(53 citation statements)

References 23 publications

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“…Thus, neutral Ps should be annihilated mostly with electrons of carbon, and consequently the o-Ps profile similar to that of the C group is obtained [4]. Essentially, the same values of S(t) parameter at the higher age between PS and PES consistent with our earlier data [4] suggest that the chemical environment around free volumes in the two polymers are very similar to each other and are largely composed of C atoms. On the other hand, the S(t) parameters of o-Ps for ETFE are well distinguishable from other two polymers.…”

Section: Resultssupporting

confidence: 79%

“…The correlation has been found to be classified into the following groups depending on the chemical element which polymers contain: (1) polymers consisting of only carbon and hydrogen, (2) oxygen-containing polymers, and (3) fluorine-containing polymers [3]. In addition, low energy Ps formed by recombination of weakly bound Mott-Wannier (MW) positron-electron pairs with large separations becomes visible by the S−I 3 correlation [4].…”

Section: Introductionmentioning

confidence: 99%

“…We have systematically investigated Ps formation in polymers by employing coincident Doppler broadening and positron lifetime spectroscopy [3,4]. A correlation between Doppler broadening line-shape S parameter and ortho-positronium fraction, I 3 (S−I 3 correlation) [5] has been introduced to examine intrinsic momentum distributions of positrons (e + ), para-positronium (p-Ps), and orthopositronium (o-Ps).…”

Section: Introductionmentioning

confidence: 99%

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Positron and Positronium Annihilation in Polymers Studied by Age-Momentum Correlation Spectroscopy

et al. 2008

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Positron (e + ) and positronium (Ps) annihilation processes in polymers are studied by positron age-momentum correlation spectroscopy, which can sensitively probe momentum distributions of e + , p-Ps, and o-Ps. For polyether sulfone and ethylene tetrafluoroethylene copolymer belonging to oxygen-containing polymers (O group) and fluorine-containing polymers (F group), respectively, significant effects of positron trapping by polar element are observed. The Doppler profile of o-Ps pick-off annihilation is strongly influenced by F atoms, giving rise to anomalous broadening. The results are discussed together with our previous data of the S−I 3 correlation in order to explore the feasibility of chemical analysis around the free volumes by age-momentum correlation spectroscopy.

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Section: Resultssupporting

confidence: 79%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Positron and Positronium Annihilation in Polymers Studied by Age-Momentum Correlation Spectroscopy

et al. 2008

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“…This technique is sensitive to voids and can detect isolated and buried pores as small as 0.3 nm (44,45). In amorphous porous IGZO films, the implanted positrons interact with electrons to form positronium (Ps) atoms that enable nanometer-scale porosity mapping over the entire film thickness.…”

Section: Significancementioning

confidence: 99%

Spray-combustion synthesis: Efficient solution route to high-performance oxide transistors

Smith²,

Zhou

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

181

186

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Metal-oxide (MO) semiconductors have emerged as enabling materials for next generation thin-film electronics owing to their high carrier mobilities, even in the amorphous state, large-area uniformity, low cost, and optical transparency, which are applicable to flat-panel displays, flexible circuitry, and photovoltaic cells. Impressive progress in solution-processed MO electronics has been achieved using methodologies such as sol gel, deep-UV irradiation, preformed nanostructures, and combustion synthesis. Nevertheless, because of incomplete lattice condensation and film densification, high-quality solution-processed MO films having technologically relevant thicknesses achievable in a single step have yet to be shown. Here, we report a low-temperature, thickness-controlled coating process to create high-performance, solution-processed MO electronics: spray-combustion synthesis (SCS). We also report for the first time, to our knowledge, indium-gallium-zinc-oxide (IGZO) transistors having densification, nanoporosity, electron mobility, trap densities, bias stability, and film transport approaching those of sputtered films and compatible with conventional fabrication (FAB) operations. etal-oxide (MO) semiconductors, especially in amorphous phases, represent an appealing materials family for next generation electronics owing to their high carrier mobilities, good environmental/thermal stability, mechanical flexibility, and excellent optical transparency (1-3). MO films complement organic semiconductors (4, 5), carbon/oxide nanomaterials (6), and flexible silicon (7, 8) for enabling new technologies, such as flexible displays and printed sensors. For fabricating high-performance electronics with acceptable fidelity, conventional processes require capital-intensive physical/chemical vapor deposition techniques. Capitalizing on the solubility of MO precursors in common solvents, solution methods have been used to fabricate semiconducting MO layers for thin-film transistors (TFTs). However, the fabrication process and field-effect mobilities of these TFTs are not competitive with the corresponding vapor-deposited (e.g., sputtered) devices (9), and developing routes to solution-derived MO TFTs with technologically relevant thicknesses and performance comparable to state of the art vapor-deposited devices is a critical milestone for MO electronics evolution.Sol-gel techniques are used extensively for MO film growth, including films for high-performance TFTs (10-13). However, the required sol-gel condensation, densification, and impurity removal steps typically require >400-500°C processing temperatures, which are incompatible with inexpensive glasses and typical flexible plastic substrates (14). Progress toward significantly reducing the processing temperatures of sol gel-derived MO films has afforded excellent TFT mobilities; however, achieving both reproducible high-performance and stable device operation remains an unsolved issue for Ga-containing materials (15). Sol-gel on-a-chip for indium-zinc-oxide (3) and deep-UV ...

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“…Measurements of the Doppler shifts by γ-ray energy spectroscopy with high purity Ge detector make it possible to obtain information on the momentum distribution of the positron-electron annihilation pairs. The momentum distribution of o-Ps is broadened centered at 511 keV because the pick-off annihilation is influenced by electrons bound to the surrounding molecules [22]- [23]. Thus, the momentum distribution of o-Ps pick-off annihilation provides the information on electronic states of pore surfaces.…”

Section: Introductionmentioning

confidence: 99%