2020/08/17 by M. Molina-Ruiz, Y. J. Rosen, H. C. Jacks +6
Engineering · Materials Science · Physics and Astronomy · #Amorphous solid #Dielectric #Dielectric loss #Dipole #Electron energy loss spectroscopy #Loss factor #Quantum tunnelling #Semiconductor materials and devices #Silicon #Silicon Nanostructures and Photoluminescence #Thin-Film Transistor Technologies #cond-mat.mtrl-sci
paper · pdf · doi:10.1103/physrevmaterials.5.035601
published as Phys. Rev. Materials 5, 035601 (2021) · 17 pages, 4 figures, 1 table
arxiv created 2020/08/17 · openalex created_date 2020/08/21 · openalex publication_date 2021/03/03 · arxiv updated 2021/03/10 · openalex updated_date 2026/08/06
Amorphous silicon contains tunneling two-level systems, which are the dominant energy loss mechanisms for amorphous solids at low temperatures. These two-level systems affect both mechanical and electromagnetic oscillators and are believed to produce thermal and electromagnetic noise and energy loss. However, it is unclear whether the two-level systems that dominate mechanical and dielectric losses are the same; the former relies on the coupling between phonons and two-level systems, with an elastic field coupling constant \ensuremathγ while the latter depends on a two-level systems dipole moment p0, which couples to the electromagnetic field. Mechanical and dielectric loss measurements as well as structural characterization were performed on amorphous silicon thin films grown by electron beam deposition with a range of growth parameters. Samples grown at 425 ^\ensuremath∘C show a large reduction of mechanical loss (34 times) and a far smaller reduction of dielectric loss (2.3 times) compared to those grown at room temperature. Additionally, mechanical loss shows lower loss for thicker films, while dielectric loss shows lower loss for thinner films. Analysis of these results indicate that mechanical loss correlates with atomic density, while dielectric loss correlates with dangling-bond density, suggesting a different origin for these two energy dissipation processes in amorphous silicon.