{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T01:31:58Z","timestamp":1760059918810,"version":"build-2065373602"},"reference-count":22,"publisher":"MDPI AG","issue":"14","license":[{"start":{"date-parts":[[2025,7,18]],"date-time":"2025-07-18T00:00:00Z","timestamp":1752796800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Portuguese Foundation for Science and Technology","award":["SFRH\/BD\/141462\/2018","COVID\/BD\/153002\/2022","SFRH\/BD\/137529\/2018","COVID\/BD\/153232\/2023","UIDB\/04436\/2020","UIDP\/04436\/2020"],"award-info":[{"award-number":["SFRH\/BD\/141462\/2018","COVID\/BD\/153002\/2022","SFRH\/BD\/137529\/2018","COVID\/BD\/153232\/2023","UIDB\/04436\/2020","UIDP\/04436\/2020"]}]},{"name":"Portuguese Foundation for Science and Technology","award":["SFRH\/BD\/141462\/2018","COVID\/BD\/153002\/2022","SFRH\/BD\/137529\/2018","COVID\/BD\/153232\/2023","UIDB\/04436\/2020","UIDP\/04436\/2020"],"award-info":[{"award-number":["SFRH\/BD\/141462\/2018","COVID\/BD\/153002\/2022","SFRH\/BD\/137529\/2018","COVID\/BD\/153232\/2023","UIDB\/04436\/2020","UIDP\/04436\/2020"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Nanomaterials"],"abstract":"<jats:p>Two-dimensional (2D) materials have been proposed for use in a multitude of applications, with graphene being one of the most well-known 2D materials. Despite their potential to contribute to innovative solutions, the fabrication of such devices still faces significant challenges. One of the key challenges is the fabrication at a wafer-level scale, a fundamental step for allowing reliable and reproducible fabrication of a large volume of devices with predictable properties. Overcoming this barrier will allow further integration with sensors and actuators, as well as enabling the fabrication of complex circuits based on 2D materials. This work presents the fabrication steps for a process that allows the on-wafer fabrication of active and passive radiofrequency (RF) devices enabled by graphene. Two fabrication processes are presented. In the first one, graphene is transferred to a back gate surface using critical point drying to prevent cracks in the graphene. In the second process, graphene is transferred to a flat surface planarized by ion milling, with the gate being buried beneath the graphene. The fabrication employs a damascene-like process, ensuring a flat surface that preserves the graphene lattice. RF transistors, passive RF components, and antennas designed for backscatter applications are fabricated and measured, illustrating the versatility and potential of the proposed method for 2D material-based RF devices. The integration of graphene on devices is also demonstrated in an antenna. This aimed to demonstrate that graphene can also be used as a passive device. Through this device, it is possible to measure different backscatter responses according to the applied graphene gating voltage, demonstrating the possibility of wireless sensor development. With the proposed fabrication processes, a flat graphene with good quality is achieved, leading to the fabrication of RF active devices (graphene transistors) with intrinsic fT and fmax of 14 GHz and 80 GHz, respectively. Excellent yield and reproducibility are achieved through these methods. Furthermore, since the graphene membranes are grown by Chemical Vapor Deposition (CVD), it is expected that this process can also be applied to other 2D materials.<\/jats:p>","DOI":"10.3390\/nano15141119","type":"journal-article","created":{"date-parts":[[2025,7,18]],"date-time":"2025-07-18T11:12:34Z","timestamp":1752837154000},"page":"1119","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Wafer-Level Fabrication of Radiofrequency Devices Featuring 2D Materials Integration"],"prefix":"10.3390","volume":"15","author":[{"given":"Vitor","family":"Silva","sequence":"first","affiliation":[{"name":"CMEMS\u2014Center for Microelectromechanical Systems, University of Minho, Campus de Azur\u00e9m, 4800-058 Guimar\u00e3es, Portugal"},{"name":"LABBELS\u2014Associate Laboratory, 4710-057 Braga, Portugal"},{"name":"INL\u2014International Iberian Nanotechnology Laboratory, Av. Mestre Jos\u00e9 Veiga, 4715-330 Braga, Portugal"}]},{"given":"Ivo","family":"Colmiais","sequence":"additional","affiliation":[{"name":"CMEMS\u2014Center for Microelectromechanical Systems, University of Minho, Campus de Azur\u00e9m, 4800-058 Guimar\u00e3es, Portugal"},{"name":"LABBELS\u2014Associate Laboratory, 4710-057 Braga, Portugal"},{"name":"INL\u2014International Iberian Nanotechnology Laboratory, Av. Mestre Jos\u00e9 Veiga, 4715-330 Braga, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2394-2119","authenticated-orcid":false,"given":"Hugo","family":"Dinis","sequence":"additional","affiliation":[{"name":"CMEMS\u2014Center for Microelectromechanical Systems, University of Minho, Campus de Azur\u00e9m, 4800-058 Guimar\u00e3es, Portugal"},{"name":"LABBELS\u2014Associate Laboratory, 4710-057 Braga, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5622-7760","authenticated-orcid":false,"given":"J\u00e9r\u00f4me","family":"Borme","sequence":"additional","affiliation":[{"name":"INL\u2014International Iberian Nanotechnology Laboratory, Av. Mestre Jos\u00e9 Veiga, 4715-330 Braga, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9875-6188","authenticated-orcid":false,"given":"Pedro","family":"Alpuim","sequence":"additional","affiliation":[{"name":"INL\u2014International Iberian Nanotechnology Laboratory, Av. Mestre Jos\u00e9 Veiga, 4715-330 Braga, Portugal"},{"name":"Center of Physics, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2177-7321","authenticated-orcid":false,"given":"Paulo M.","family":"Mendes","sequence":"additional","affiliation":[{"name":"CMEMS\u2014Center for Microelectromechanical Systems, University of Minho, Campus de Azur\u00e9m, 4800-058 Guimar\u00e3es, Portugal"},{"name":"LABBELS\u2014Associate Laboratory, 4710-057 Braga, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2025,7,18]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"13283","DOI":"10.1039\/C4NR03670K","article-title":"Nanoelectronic Circuits Based on Two-Dimensional Atomic Layer Crystals","volume":"6","author":"Lee","year":"2014","journal-title":"Nanoscale"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"235402","DOI":"10.1103\/PhysRevB.80.235402","article-title":"Carrier Scattering, Mobilities, and Electrostatic Potential in Monolayer, Bilayer, and Trilayer Graphene","volume":"80","author":"Zhu","year":"2009","journal-title":"Phys. Rev. B Condens. Matter Mater Phys."},{"key":"ref_3","unstructured":"Wu, Y.Q., Farmer, D.B., Valdes-Garcia, A., Zhu, W.J., Jenkins, K., Dimitrakopoulos, C., Avouris, P., and Lin, Y.-M. (2011, January 5\u20137). Record High RF Performance for Epitaxial Graphene Transistors. Proceedings of the International Electron Devices Meeting (IEDM), Washington, DC, USA."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"026402","DOI":"10.1088\/1361-6633\/ac953e","article-title":"2D-Materials-Integrated Optoelectromechanics: Recent Progress and Future Perspectives","volume":"86","author":"Peng","year":"2023","journal-title":"Rep. Prog. Phys."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"032010","DOI":"10.1088\/2631-7990\/acd88d","article-title":"Radiofrequency Sensing Systems Based on Emerging Two-Dimensional Materials and Devices","volume":"5","author":"Xue","year":"2023","journal-title":"Int. J. Extrem. Manuf."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"100409","DOI":"10.1016\/j.flatc.2022.100409","article-title":"Towards RF Graphene Devices: A Review","volume":"35","author":"Colmiais","year":"2022","journal-title":"FlatChem"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"11588","DOI":"10.1073\/pnas.1205696109","article-title":"High-Frequency Self-Aligned Graphene Transistors with Transferred Gate Stacks","volume":"109","author":"Cheng","year":"2012","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Gao, Q., Xiong, X., Li, X., and Wu, Y. (2018, January 6\u20138). High Performance Double-Gate Graphene Radio-Frequency Transistors. 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Nanotechnol."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"102106","DOI":"10.1063\/1.4914926","article-title":"Bottom-Gate Coplanar Graphene Transistors with Enhanced Graphene Adhesion on Atomic Layer Deposition Al2O3","volume":"106","author":"Park","year":"2015","journal-title":"Appl. Phys. Lett."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"43113","DOI":"10.1063\/1.3474613","article-title":"Scanning Raman Spectroscopy of Graphene Antidot Lattices: Evidence for Systematic p-Type Doping","volume":"97","author":"Heydrich","year":"2010","journal-title":"Appl. Phys. Lett."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"132","DOI":"10.1021\/nl103015w","article-title":"Probing Charge Transfer at Surfaces Using Graphene Transistors","volume":"11","author":"Levesque","year":"2011","journal-title":"Nano Lett."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"085302","DOI":"10.1088\/0953-8984\/28\/8\/085302","article-title":"Graphene Field-Effect Transistor Array with Integrated Electrolytic Gates Scaled to 200 Mm","volume":"28","author":"Vieira","year":"2016","journal-title":"J. Phys. Condens. Matter"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"8076","DOI":"10.1039\/C5NR01126D","article-title":"Scaling of Graphene Integrated Circuits","volume":"7","author":"Bianchi","year":"2015","journal-title":"Nanoscale"},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Cabral, P.D., Domingues, T., Machado, G., Chicharo, A., Cerqueira, F., Fernandes, E., Athayde, E., Alpuim, P., and Borme, J. (2020). Clean-Room Lithographical Processes for the Fabrication of Graphene Biosensors. Materials, 13.","DOI":"10.3390\/ma13245728"},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Abrantes, M., Rodrigues, D., Domingues, T., Nemala, S.S., Monteiro, P., Borme, J., Alpuim, P., and Jacinto, L. (2022). Ultrasensitive Dopamine Detection with Graphene Aptasensor Multitransistor Arrays. J. Nanobiotechnol., 20.","DOI":"10.1186\/s12951-022-01695-0"},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Palacio, I., Moreno, M., N\u00e1\u00f1ez, A., Purwidyantri, A., Domingues, T., Cabral, P.D., Borme, J., Marciello, M., Mendieta-Moreno, J.I., and Torres-V\u00e1zquez, B. (2023). Attomolar Detection of Hepatitis C Virus Core Protein Powered by Molecular Antenna-like Effect in a Graphene Field-Effect Aptasensor. Biosens. Bioelectron., 222.","DOI":"10.1016\/j.bios.2022.115006"},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Dinis, H., Colmiais, I., and Mendes, P.M. (2017, January 26\u201330). A Multiantenna Approach to Maximize Wireless Power Transfered to Implantable Devices. Proceedings of the 2017 International Applied Computational Electromagnetics Society Symposium-Italy (ACES), Firenze, Italy.","DOI":"10.23919\/ROPACES.2017.7916363"},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Colmiais, I., Dinis, H., and Mendes, P.M. (2019, January 22\u201323). WPT System for Implantable Devices Using a Phased Array and Tracking Algorithm for Freely Moving Rats. Proceedings of the 2019 IEEE 6th Portuguese Meeting on Bioengineering (ENBENG), Lisbon, Portugal.","DOI":"10.1109\/ENBENG.2019.8692495"},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Dinis, H., Colmiais, I., and Mendes, P.M. (2017). Extending the Limits of Wireless Power Transfer to Miniaturized Implantable Electronic Devices. Micromachines, 8.","DOI":"10.3390\/mi8120359"},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Dinis, H., Colmiais, I., and Mendes, P.M. (2019, January 23\u201326). Design and Validation of a Six-Antenna WPT System with Tracking Capabilites for Biomedical Devices. Proceedings of the 2019 17th IEEE International New Circuits and Systems Conference (NEWCAS), Munich, Germany.","DOI":"10.1109\/NEWCAS44328.2019.8961219"}],"container-title":["Nanomaterials"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2079-4991\/15\/14\/1119\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T18:12:06Z","timestamp":1760033526000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2079-4991\/15\/14\/1119"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,7,18]]},"references-count":22,"journal-issue":{"issue":"14","published-online":{"date-parts":[[2025,7]]}},"alternative-id":["nano15141119"],"URL":"https:\/\/doi.org\/10.3390\/nano15141119","relation":{},"ISSN":["2079-4991"],"issn-type":[{"type":"electronic","value":"2079-4991"}],"subject":[],"published":{"date-parts":[[2025,7,18]]}}}