Showing papers by "Masashi Kurosawa published in 2023"
TL;DR: In this article , the diameter of Si-NCs was changed by varying the thickness of the a-SiO x layer from 3 to 50 nm and the electrical conductivity was increased in the t a -SiOx range of 3 to 13 nm and saturated around 5.7 kS·m−1.
Abstract: Boron-doped silicon nanocrystals (Si-NCs)/amorphous silicon oxide (a-SiO y ) multilayers were prepared by plasma-enhanced chemical vapor deposition and post-annealing of boron-doped Si-rich amorphous silicon oxide (a-SiO x ) and a-SiO y multilayers. The diameter of Si-NCs was changed by varying the thickness of the a-SiO x layer (t a-SiOx ) from 3 to 50 nm. The electrical conductivity (σ) was increased in the t a-SiOx range of 3 to 13 nm and saturated around 5.7 kS·m−1. This tendency corresponds to crystal volume fraction in the Si-NCs multilayers. Seebeck coefficient (S) was almost constant at 230 μV·K−1 and showed no dependence on t a-SiOx . Thermal conductivity (κ) was in the range of 1.4–1.5 W·m−1·K−1 and almost independent of t a-SiOx , which is much lower than that of bulk Si. A maximum power factor of 0.33 mW·m−1·K−2 was obtained at t a-SiOx = 13 nm.
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TL;DR: In this paper , lattice-matched Si1−y Ge y surfaces using molecular beam epitaxy were used to realize epitaxial Si 1−x Sn x layers with various Sn contents.
Abstract: Silicon tin (Si1−x Sn x ) layers with an Sn content of 11%, which is almost 100 times the solid solubility limit, have been successfully grown on lattice-matched Si1−y Ge y surfaces using molecular beam epitaxy. The crystallographic analyses revealed that the Sn precipitation did not occur during the growth, even using a deposition temperature (T d) exceeding the Si-Sn eutectic point (231.97 °C). Further, the epitaxial thickness could be increased from 20 to 100 nm with T d from 250 to 350 °C without any Sn precipitation. Utilizing a lattice-matched Si1−y Ge y buffer will be a powerful tool to realize epitaxial Si1−x Sn x layers with various Sn contents.
TL;DR: In this paper , the self-organized formation of Ge1−xSnx quantum dots (QDs) on insulators based on a simple sputtering process and considered their luminescence properties was examined.
Abstract:
In this study, we examined the self-organized formation of Ge1−xSnx quantum dots (QDs) on insulators based on a simple sputtering process and considered their luminescence properties. First, we systematically discussed the control factors in the self-organized formation of Ge1−xSnx QDs; the introduced Sn content and the deposition temperature should be related to the surface-migration of Sn atoms. Under sufficiently controlled conditions, we achieved the self-organized formation of Ge1−xSnx QDs surrounded by amorphous-like shells with a dot size of 9.3 nm, Sn content of 19 ± 10%, and dot density of 1.5 × 1011 cm−2 and they showed a 2.0-µm photoluminescence peak at room temperature. Furthermore, the formation of multilayered Ge1−xSnx QDs structures was demonstrated, and they exhibited excellent thermal stability up to 400 °C while maintaining a dot-like morphology without causing the agglomeration. Therefore, the self-organized formation of Ge1−xSnx QDs is useful for realizing light-emitting devices for optical interconnects.
TL;DR: In this paper , the authors investigated the heteroepitaxial growth of CaGe2, the precursor of the GeH, on a high resistive substrate of FZ-Si(111) using a molecular beam epitaxy with the deposition temperature (Tdepo) as a variable.