Optical dielectric constants are critical to modeling the electronic and optical properties of materials. Silver, as a noble metal with low loss, has been extensively investigated. The recently developed epitaxial growths of single crystalline Ag on dielectric substrates have prompted efforts to characterize their intrinsic optical dielectric function. In this paper, we report spectral ellipsometry measurements and analysis of a thick, epitaxially-grown, single-crystalline Ag film. We focus on the range of 0.18 – 1.0 eV or 1.24 – 7 µm, an energy and wavelength range that has not been examined previously using epitaxial films. We compare the extracted dielectric constants and the predicted optical performances with previous measurements. The loss is appreciably lower than the widely quoted Palik’s optical constants (i.e., up to a factor of 2) in the infrared frequency range. The improved knowledge of fundamental optical properties of the high-quality epitaxial Ag film will have a broad impact on simulations and practical applications based on Ag in the long wavelength range.
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Broadband Characterization of Silicate Materials for Potential 5G/6G Applications
This article provides a broadband dielectric characterization of different silicate substrates up to 115 GHz, to fill the gap in the properties of different kinds of glasses in a broad part of the mm-wave spectrum. Both the internal structure (crystalline or amorphous) and the chemistry of the substrates influence the permittivity and loss tangent of the material. Quartz and sapphire are crystalline materials that exhibit a low loss in the mm-wave frequency range. Amorphous silicates generally have higher loss values than crystalline materials, and within the glasses, the level of impurities added also affects the dielectric loss. Several characterization techniques have been employed to cover a broad frequency band. The limitations of the different characterization techniques are also included. Once the dielectric properties of substrates are characterized, a metasurface has been designed and fabricated at 100 GHz to increase the reflection in window glass and provide coverage on areas that would otherwise be shadowed. The measurement results are in good agreement with the simulations.
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- PAR ID:
- 10478821
- Publisher / Repository:
- IEEE
- Date Published:
- Journal Name:
- IEEE Transactions on Instrumentation and Measurement
- Volume:
- 72
- ISSN:
- 0018-9456
- Page Range / eLocation ID:
- 1 to 8
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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