Two-level systems in evaporated amorphous silicon
| Autor: | Xiao Liu, Thomas Metcalf, Frances Hellman, Julie Karel, H. C. Jacks, Daniel Queen |
|---|---|
| Rok vydání: | 2015 |
| Předmět: |
Amorphous silicon
Materials science FOS: Physical sciences chemistry.chemical_compound Materials Chemistry Internal friction Atomic density Applied Physics Condensed Matter - Materials Science Condensed matter physics Specific heat Materials Science (cond-mat.mtrl-sci) Disordered Systems and Neural Networks (cond-mat.dis-nn) Materials Engineering Condensed Matter - Disordered Systems and Neural Networks Orders of magnitude (numbers) Condensed Matter Physics Electronic Optical and Magnetic Materials Amorphous solid Two-level systems Crystallography chemistry Ceramics and Composites |
| Zdroj: | Queen, DR; Liu, X; Karel, J; Jacks, HC; Metcalf, TH; & Hellman, F. (2015). Two-level systems in evaporated amorphous silicon. Journal of Non-Crystalline Solids, 426, 19-24. doi: 10.1016/j.jnoncrysol.2015.06.020. UC Berkeley: Retrieved from: http://www.escholarship.org/uc/item/0p80z87j |
| Popis: | © 2015 Elsevier B.V. All rights reserved. In e-beam evaporated amorphous silicon (a-Si), the densities of two-level systems (TLS), n0 and P¯, determined from specific heat C and internal friction Q- 1 measurements, respectively, have been shown to vary by over three orders of magnitude. Here we show that n0 and P¯ are proportional to each other with a constant of proportionality that is consistent with the measurement time dependence proposed by Black and Halperin and does not require the introduction of additional anomalous TLS. However, n0 and P¯ depend strongly on the atomic density of the film (nSi) which depends on both film thickness and growth temperature suggesting that the a-Si structure is heterogeneous with nanovoids or other lower density regions forming in a dense amorphous network. A review of literature data shows that this atomic density dependence is not unique to a-Si. These findings suggest that TLS are not intrinsic to an amorphous network but require a heterogeneous structure to form. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|