Thermal annealing of a-Si/Au superlattice thin films

Aono, Masami; Takahashi, Masakazu; Takiguchi, Hiroaki; Kitazawa, Nobuaki; Watanabe, Yoshihisa

doi:10.1016/j.jnoncrysol.2011.12.088

Cited by 8 publications

(5 citation statements)

References 26 publications

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“…The intensity of Au 111 Bragg reflection gradually increased with increasing temperature. The previous study [16] suggests that the morphological transformation from the layered a-Au to the c-Au nanoparticles takes place irreversibly. In contrast to the MIC in a-Si, it is emphasized that the whole volume of a-Au can transform to c-Au at around 560 K. On deposition process of Au, the confinement in the thin Au layer (t Au = 0.8 nm) below the critical size for crystal nucleation enforces the atomic arrangement to form unstable amorphous, which is far from an equilibrium state.…”

Section: Au Nanoparticle Formation By In Situ Xrdmentioning

confidence: 85%

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Au Nanoparticle Formation from Amorphous Au/Si Multilayer

Aono¹,

Abe²,

Kobayashi³

2014

JCPT

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By direct observations of transmission electron microscopy (TEM), irreversible morphological transformations of as-deposited amorphous Au/Si multilayer (a-Au/a-Si) were observed on heating. The well arrayed sequence of the multilayer changed to zigzag layered structure at 478 K (=T zig). Finally, the zigzag structure transformed to Au nanoparticles at 508 K. The distribution of the Au nanoparticles was random within the thin film. In situ X-ray diffraction during heating can clarify partial crystallization Si (c-Si) in the multilayer at 450 K (= T ML MIC), which corresponds to metal induced crystallization (MIC) from amorphous Si (a-Si) accompanying by Au diffusion. On further heating, a-Au started to crystallize at around 480 K (=T c) and gradually grew up to 3.2 nm in radius, although the volume of c-Si was almost constant. Continuous heating caused crystal Au (c-Au) melting into liquid AuSi (ℓ-AuSi) at 600 K (= T NP m), which was lower than bulk eutectic temperature (T B E = 636 5 K ±). Due to the AuSi eutectic effect, reversible phase transition between liquid and solid occurred once temperature is larger than T NP m. Proportionally to the maximum temperatures at each cycles (673, 873 and 1073 K), both T NP m and Au crystallization temperature approaches to T B E. Using a thermodynamic theory of the nanoparticle formation in the eutectic system, the relationship between T NP m and the nanoparticle size is explained.

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Section: Au Nanoparticle Formation By In Situ Xrdmentioning

confidence: 85%

“…The geometric array was generated in one Au 1−x Si x thin film on Si substrate, whose thickness is 25 nm. On the other hand, cyclic 4.2 nm a-Si and 0.8 nm a-Au multilayer showed different irreversible transformations such as nanoparticles after annealing [16]. The thin film consists of 60 layers.…”

Section: Introductionmentioning

confidence: 98%

Au Nanoparticle Formation from Amorphous Au/Si Multilayer

Aono¹,

Abe²,

Kobayashi³

2014

JCPT

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“…Since Au hardly dissolves in the crystal Si, 40) it is solidsolved in amorphous Si or precipitated as crystal Au. 41) Therefore, the Au volume does not affect the calculated d, and only affects sA. Considering the volume of Au, the volume of the basic cell of the mosaic model V cubic is…”

Section: Discussion On Quantum Effectsmentioning

confidence: 99%

Necessary conditions for superior thermoelectric power of Si/Au artificial superlattice thin-film

Watanabe

Miyazaki

Morimoto

2018

Jpn. J. Appl. Phys.

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The Si-Ge-Au ternary artificial superlattice thin-films showed superior thermoelectric power with low reproducibility. Superior thermoelectric power was only generated, when nanocrystals existed. Therefore, the origin of superior thermoelectric power was considered to be the quantum size effect of nanocrystals. However, even with the presence of nanocrystals, superior thermoelectric power was often not generated. In order to investigate the generation conditions of superior thermoelectric power in more detail, the samples were simplified to Si-Au binary artificial superlattice samples. Furthermore, annealings were carried out under conditions where nanocrystals were likely to be formed. From the results of Raman scattering spectroscopy and X-ray diffraction (XRD) analysis, the diameter of nanocrystals and the spacing between nanocrystals were calculated with an isotropic three-dimensional mosaic model. It was found that superior thermoelectric power was generated only when the diameter of nanocrystals was 11 nm or less and the spacing between nanocrystals was 3 nm or less.

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“…All thin film samples were deposited in multi source ultra-high vacuum chamber system, which was generally categorized as MBE (Molecular Beam Epitaxial) system as described previous papers [17][18][19]. Base pressure and pressure during deposition was kept 1~5×10 -6 Pa and 5× 10 -6 pa, respectively.…”

Section: Sample Preparationsmentioning

confidence: 99%

Crystallization and Reconstructive Layer Transformation of a-Si/Au Multilayer Thin Films under a Strong Gravitational Field

Aono

Miyazaki

Ogata³

et al. 2015

DDF

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There were still unclear questions in the new method that fabricate the high quality poly crystalline Si thin film from amorphous Si thin film with lower annealing temperature than conventional Si recrystallization temperature. In that recrystallization process, the recrystallization mechanism was generally explained by the MIC (Metal Induced Crystallization) of Au. In this paper, we have discussed the effects of film structure and strong gravity on recrystallization, by using conventional furnace and high-temperature ultracentrifuge furnace system. The five kinds of samples (two bilayered Si/Au thin films, two multilayered Si/Au thin films and trilayered Si/Au/Si thin film) and found the effects of structure and strong gravity. The best for crystallization was Au/Si multilayered thin film, which is almost finished to crystallize even at 673 K annealing. The strong gravity advanced and retreated the crystallization, depending to thin film structure.

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Thermal annealing of a-Si/Au superlattice thin films

Cited by 8 publications

References 26 publications

Au Nanoparticle Formation from Amorphous Au/Si Multilayer

Au Nanoparticle Formation from Amorphous Au/Si Multilayer

Necessary conditions for superior thermoelectric power of Si/Au artificial superlattice thin-film

Crystallization and Reconstructive Layer Transformation of a-Si/Au Multilayer Thin Films under a Strong Gravitational Field

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