Promotion in solid phase reaction of Pt/SiO<sub>x</sub> bilayer film by electron-orbital-selective-excitation

Yasuda, Hidehiro; Satō, Kazunori; Ichikawa, Shuhei; Imamura, Masaki; Takahashi, Kazutoshi; Mori, Hirotarô

doi:10.1039/d0ra07151j

Cited by 3 publications

(3 citation statements)

References 13 publications

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“…Researchers have reported atomic-scale disproportionation in a-SiO; in this case, a-Si-like and a-SiO 2 -like clusters are present in a-SiO . Although our results are based on electron microscopy experiments, the effect of electronic excitation on dissociation of the Si–O bond, which we verified here and in recent studies, , is not explicitly incorporated in the above-mentioned paper …”

Section: Results and Discussionmentioning

confidence: 55%

“…However, atomic reaction induced by electronic excitation is another route to promote a solid phase reaction. However, there are few examples of such reactions in inorganic materials except the following two cases: (i) decomposition of GaSb nanoparticles by 25 keV electron irradiation and (ii) Pt 2 Si formation at a Pt/amorphous silicon oxide (a-SiO x ) interface by electron irradiation (25–200 keV) − or photoirradiation (140 eV). , These reactions proceed under irradiation conditions where knock-on atomic displacement is absent, and hence, the origin of the atomic reaction is attributable to electronic excitation. Particularly in the latter case (Pt 2 Si formation), a direct reaction between Pt and SiO x by thermal annealing cannot occur, as experimentally confirmed .…”

Section: Introductionmentioning

confidence: 99%

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Athermal Solid Phase Reaction in Pt/SiO_x Thin Films Induced by Electron Irradiation

Sato

Mori

2021

ACS Omega

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Microelectronics based on Si requires metal silicide contacts. The ability to form platinum silicide (Pt 2 Si) by electronic excitation instead of thermal processes would benefit the field. We studied the effects of electron irradiation on Pt 2 Si formation in composite films—composed of Pt and amorphous silicon oxides (a-SiO x )—by transmission electron microscopy and electron diffraction. Pt 2 Si formed in Pt/a-SiO x bilayer and a-SiO x /Pt/a-SiO x sandwiched films by 75 keV electron irradiation, at 298 and 90 K. The reaction is attributable to dissociation of SiO x triggered by electronic excitation. In a-SiO x /Pt/a-SiO x sandwiched films, reflections of pure Pt were not present after irradiation, i.e., Pt was completely consumed in the reaction to form Pt 2 Si at 298 K. However, in Pt/a-SiO x bilayer films, unreacted Pt remained under the same irradiation conditions. Thus, it can be said that the extent of the interfacial area is the predominant factor in Pt 2 Si formation. The morphology of Pt islands extensively changed during Pt 2 Si formation even at 90 K. Coalescence and growth of metallic particles (Pt and Pt–Si) are not due to thermal effects during electron irradiation but to athermal processes accompanied by silicide formation. To maintain the reaction interface between metallic particles and the dissociation product (i.e., Si atoms) by electronic excitation, a considerable concomitant morphology change occurs. Elemental analysis indicates that the decrease in Si concentration near Pt is faster than the decrease in O concentration, suggesting formation of a Si depletion zone in the amorphous silicon oxide matrix associated with formation of Pt 2 Si.

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Section: Results and Discussionmentioning

confidence: 55%

Section: Introductionmentioning

confidence: 99%

Athermal Solid Phase Reaction in Pt/SiO_x Thin Films Induced by Electron Irradiation

Sato

Mori

2021

ACS Omega

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“…As mentioned in the Results section, trigonal Fe 2 Si was formed at the Fe/a-SiO x interface by electron irradiation. Figure 7 shows a schematic illustration showing the elementary processes of the interfacial reaction proposed in this study, including previous findings: 4,17 (1) electronic excitation of a-SiO x (x ∼ 1.5) (Si 3+ → Si 4+ ) by electron irradiation, (2) Auger decay of a core−hole, (3) dissociation of a Si−O bond, and (4) formation of an Fe−Si bond. The dissociation mechanism triggered by electronic excitation is similar to the case in the Knotek−Feibelman (K−F) model for oxygen ion desorption from the free surface of oxides.…”

Section: ■ Discussionmentioning

confidence: 73%

Trigonal Fe₂Si Nanosheets at Fe/Amorphous SiO_x Interfaces for Spintronic Nanodevices

Sato,

Fujii

2024

ACS Appl. Nano Mater.

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Trigonal Fe 2 Si nanosheets, which are promising candidates for spintronic nanodevices, were synthesized at the Fe/ amorphous (a-)SiO x thin film interface using electron irradiation. The formation of nanoscale silicide was confirmed at 90 K as well as at 298 K. Such a low-temperature synthesis of Fe 2 Si can be attributed to the dissociation of a-SiO x induced by electronic excitation; Si−O bonds dissociate through Auger decay of core− holes generated by electronic excitation, and then, dissociated Si atoms form Fe−Si bonds. The amount of Fe 2 Si formed at room temperature was greater than that at 90 K, suggesting that the atomic migration induced by electronic excitation involves a contribution of thermal energy. The amount of Fe 2 Si nanosheets produced indicates that the Si−O bonds are more easily dissociated by electronic excitation in a-SiO x rather than in a-SiO 2 . Formation of the Fe 2 Si nanosheets found in this study differs from the formation of an equiatomic FeSi phase predicted by thermodynamic models assuming diffusion at a planar Fe/Si interface. We propose a versatile route to selectively form metal silicide nanosheets in an electron irradiated area at temperatures below room temperature.

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Solute atom mediated crystallization of amorphous alloys

Sato,

Mori

2023

Materialia

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Promotion in solid phase reaction of Pt/SiO_x bilayer film by electron-orbital-selective-excitation

Abstract: A thermally impossible positive free energy reaction can proceed by electron-orbital-selective excitation.

Cited by 3 publications

References 13 publications

Athermal Solid Phase Reaction in Pt/SiO_x Thin Films Induced by Electron Irradiation

Athermal Solid Phase Reaction in Pt/SiO_x Thin Films Induced by Electron Irradiation

Trigonal Fe₂Si Nanosheets at Fe/Amorphous SiO_x Interfaces for Spintronic Nanodevices

Solute atom mediated crystallization of amorphous alloys

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Promotion in solid phase reaction of Pt/SiOx bilayer film by electron-orbital-selective-excitation

Abstract: A thermally impossible positive free energy reaction can proceed by electron-orbital-selective excitation.

Cited by 3 publications

References 13 publications

Athermal Solid Phase Reaction in Pt/SiOx Thin Films Induced by Electron Irradiation

Athermal Solid Phase Reaction in Pt/SiOx Thin Films Induced by Electron Irradiation

Trigonal Fe2Si Nanosheets at Fe/Amorphous SiOx Interfaces for Spintronic Nanodevices

Solute atom mediated crystallization of amorphous alloys

Contact Info

Product

Resources

About

Promotion in solid phase reaction of Pt/SiO_x bilayer film by electron-orbital-selective-excitation

Athermal Solid Phase Reaction in Pt/SiO_x Thin Films Induced by Electron Irradiation

Athermal Solid Phase Reaction in Pt/SiO_x Thin Films Induced by Electron Irradiation

Trigonal Fe₂Si Nanosheets at Fe/Amorphous SiO_x Interfaces for Spintronic Nanodevices