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| 題名: | Evolution of thermal, structural, and optical properties of SiGe superlattices upon thermal treatment |
| 作者: | 李勝偉;Chen, Peixuan;Etzelstorfer, Tanja;Hackl, Florian;Katcho, Nebil A.;Chang, Hung-Tai;Nausner, Lukas;Lee, Sheng-Wei;Fromherz, Thomas;Stangl, Julian;Schmidt, Oliver G.;Mingo, Natalio;Rastelli, Armando |
| 貢獻者: | 工學院材料科學與工程研究所 |
| 關鍵詞: | 3-omega method;alloys;Annealing;Evolution;Heat transfer;Heat treatment;photoluminescence;SiGe;Silicon germanides;Superlattices;Thermal conductivity;Transmission electron microscopy |
| 日期: | 2016-03-01 |
| 上傳時間: | 2026-04-23 11:34:26 (UTC+8) |
| 出版者: | Wiley-VCH Verlag;Weinheim: Blackwell Publishing Ltd |
| 摘要: | 摘要： We investigate the evolution of the cross‐plane thermal conductivity κ of a SiGe superlattice (SL) as it is gradually converted into an alloy via post‐growth thermal treatment at temperatures varying from 650 to 1000 °C. X‐ray diffraction (XRD), transmission electron microscopy (TEM), secondary‐ion‐mass‐spectroscopy (SIMS), and photoluminescence (PL) spectroscopy measurements are used as complementary tools to gain insight into the structural properties of our SL and their evolution upon annealing. While the SL structure is preserved up to temperatures of ∼850 °C, full alloying is observed for higher temperatures. The thermal conductivity data, collected with differential 3ω method, show a monotonic increase of κ from ∼4.5 W/m K up to the values expected for a thin‐film alloy. To understand the results, we compute the phonon mean‐free‐path (MFP) spectra using the experimentally determined composition profiles as input. The calculated thermal conductivity values are in good agreement with the experimental data and show that the increase of thermal conductivity is due to a gradual increase of MFP of low‐to‐mid‐frequency phonons, i.e., to a weakening of interface scattering for alloyed SLs. The calculations also allow us to address finite‐thickness effects on the measured thermal conductivity data. Although the used SL had a total thickness of only ∼250 nm, its thermal conductivity can be assumed to coincide with that of a “bulk” (infinitely thick) SL prior to annealing. As interdiffusion increases, boundary scattering at the film/substrate interface becomes relevant and leads to a slow increase of κ. Besides its fundamental relevance, this work shows that the thermal stability of superlattices is limited, and that sizeable structural changes (including defect formation) occur already at operation temperatures of ∼650 °C.
其他題名： Phys. Status Solidi A
出版者： Weinheim: Blackwell Publishing Ltd
出版日期： 2016-03
出處： Physica status solidi. A, Applications and materials science, 2016-03, Vol.213 (3), p.533-540
版權： 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim
版權： 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
識別號： ISSN: 1862-6300
識別號： EISSN: 1862-6319
識別號： DOI: 10.1002/pssa.201532468 |
| 顯示於類別: | [材料科學與工程研究所 ] 期刊論文
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