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Nano Research

Article Title

Lightweight porous silica foams with extreme-low dielectric permittivity and loss for future 6G wireless communication technologies

Authors

Petra S. Pálvölgyi, Microelectronics Research Unit, Faculty of Information and Electrical Engineering, University of Oulu, P. O. Box 4500, FI-90570 Oulu, Finland
Daniel Sebők, Interdisciplinary Excellence Centre, Department of Applied and Environmental Chemistry, University of Szeged, Rerrich Béla tér 1, H-6720 Szeged, Hungary
Imre Szenti, Interdisciplinary Excellence Centre, Department of Applied and Environmental Chemistry, University of Szeged, Rerrich Béla tér 1, H-6720 Szeged, Hungary
Eva Bozo, Microelectronics Research Unit, Faculty of Information and Electrical Engineering, University of Oulu, P. O. Box 4500, FI-90570 Oulu, Finland
Henri Ervasti, Microelectronics Research Unit, Faculty of Information and Electrical Engineering, University of Oulu, P. O. Box 4500, FI-90570 Oulu, Finland
Olli Pitkänen, Microelectronics Research Unit, Faculty of Information and Electrical Engineering, University of Oulu, P. O. Box 4500, FI-90570 Oulu, Finland
Jari Hannu, Microelectronics Research Unit, Faculty of Information and Electrical Engineering, University of Oulu, P. O. Box 4500, FI-90570 Oulu, Finland
Heli Jantunen, Microelectronics Research Unit, Faculty of Information and Electrical Engineering, University of Oulu, P. O. Box 4500, FI-90570 Oulu, Finland
Marko E. Leinonen, Centre for Wireless Communications, University of Oulu, P. O. Box 4500, FI-90570 Oulu, Finland
Sami Myllymäki, Microelectronics Research Unit, Faculty of Information and Electrical Engineering, University of Oulu, P. O. Box 4500, FI-90570 Oulu, Finland
Akos Kukovecz, Interdisciplinary Excellence Centre, Department of Applied and Environmental Chemistry, University of Szeged, Rerrich Béla tér 1, H-6720 Szeged, Hungary
Krisztian Kordas, Microelectronics Research Unit, Faculty of Information and Electrical Engineering, University of Oulu, P. O. Box 4500, FI-90570 Oulu, Finland

Keywords

low-permittivity materials, low-loss dielectrics, templated sol-gel synthesis, silica foams, 6G telecommunication

Abstract

In the next generation wireless communication systems operating at near terahertz frequencies, dielectric substrates with the lowest possible permittivity and loss factor are becoming essential. In this work, highly porous (98.9% ± 0.1%) and lightweight silica foams (0.025 ± 0.005 g/cm3), that have extremely low relative permittivity (εr = 1.018 ± 0.003 at 300 GHz) and corresponding loss factor (tan δ < 3 × 10-4 at 300 GHz) are synthetized by a template-assisted sol-gel method. After dip-coating the slabs of foams with a thin film of cellulose nanofibers, sufficiently smooth surfaces are obtained, on which it is convenient to deposit electrically conductive planar thin films of metals important for applications in electronics and telecommunication devices. Here, micropatterns of Ag thin films are sputtered on the substrates through a shadow mask to demonstrate double split-ring resonator metamaterial structures as radio frequency filters operating in the sub-THz band.

Publisher

Tsinghua University Press

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