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TY - THES AU - Reato, Eros TI - 2D materials technology for RF integrated electronics PB - Rheinisch-Westfälische Technische Hochschule Aachen VL - Dissertation CY - Aachen M1 - RWTH-2025-00435 SP - 1 Online-Ressource : Illustrationen PY - 2024 N1 - Veröffentlicht auf dem Publikationsserver der RWTH Aachen University 2025 N1 - Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2024 AB - Flexible electronics is a promising field of research, whose potential has been explored in recent years. The technological benefits that a fully developed flexible electronics industry can bring are enormous, ranging from small, connected and lightweight wearable devices to flexible displays and batteries. Among the materials suitable for such applications, are organic semiconductors, graphene and other 2D materials. The semiconducting transition metal dichalcogenide MoS plays an important role due to its excellent mechanical strength and flexibility. In this context, MoS layers grown by chemical vapor deposition (CVD) are of particular interest compared to mechanically exfoliated flakes, as this technique enables large-scale production. To achieve this, novel processes and characterization routines need to be developed to fully exploit the potential of the new materials on the new substrates. In fact, some of the characterization methods used to investigate the quality of standard silicon devices have yet to be fully understood and need further development for the characterization and modeling of the new materials. The goal of this dissertation is to demonstrate the feasibility of flexible 2D materials-based radio frequency (RF) devices and circuits. A fundamental requirement for this goal is the fabrication of high-performance devices and the development of integration strategies that enable the realization of complex circuits. Furthermore, the careful characterization of MoS, its relationship with the dielectric environment and the consequent understanding of the physical phenomena due to defects and intrinsic material properties is targeted as a fundamental step towards the development of optimized devices. This goal has been investigated through the development of a new theoretical model for the analysis of electrical measurements and through the experimental fabrication and the characterization in DC and RF of prototype devices and circuits. In this dissertation, RF-flexible MoS-based field-effect transistors (FETs) and circuits operating in the range on flexible substrates are fabricated and characterized. The MoS materials used in this work are exclusively CVD, while the metals and oxides are deposited using scalable process technology. The fabrication and analysis of test structures using electrical, optical, and physical measurement techniques allowed the modeling of the electrical relationships between the MoS channel material and the gate oxide. <b>The new model, together with admittance measurements, allowed to study the interplay between the MoS and its surrounding dielectric environment.</b> This provided a deeper understanding of the charge trapping phenomena and is powerful tool to evaluate the impact of the deposition of the dielectrics in the fabrication processes of 2D-based FETs. The results of this study were presented at the 2021 Silicon Nanoelectronics Workshop (oral, online) and with a poster at the 53rd Semiconductor Interface Specialists Conference (2022) in San Diego, CA, USA, among others. This work was peer-reviewed and will be published in 2025 in IEEE Transactions on Electron Devices. AB - <div class="p"><!----></div> AB - The suitability of MoS for high frequency applications was demonstrated by fabricating RF devices on a flexible polyimide (PI) substrate, comparing monolayer and multilayer MoS as channel materials. The devices were characterized in DC and RF, showing maximum f<sub>\text</sub>t and f<sub>\text</sub>max of and . The devices were subsequently tested in a power detector circuit configuration, thus realizing <b>the first MoS-based power detector to date.</b> The detectors have high responsivities up to at for the multilayer MoS, and at for the monolayer material. The results were presented at the 2022 Graphene Conference (oral) in Aachen, among others, and published in a journal (Advanced Materials, equal contribution).Nanoscale fabrication offers an improvement in RF performance achieved through the successful integration of electron beam lithography (EBL) with flexible substrates, scaling semiconductor channels to the nanometer scale. Although EBL is not a standard semiconductor manufacturing process, it has been used to explore the potential of nanoscale devices. <b>The improvement in RF performance is more than tenfold, with the f<sub>\text</sub>max reaching and the best transconductance reported to date for an RF MoS device on a flexible substrate, for an long device.</b> The devices were realized at Stanford University (CA, USA) during a research stay abroad. The results were presented at the 2024 Device Research Conference (DRC) (oral, equal contribution) at College Park, MD, USA. Finally, <b>for the first time, MoS RF devices were integrated together with existing flexible metal-insulator-graphene (MIG) diode technology on the same substrate</b>, paving the way for the design of circuits that take advantage of both materials. The integrated devices show transconductance up to for a long FET, and mobilities up to with the four probe measurements. These results show that our technology yields integrated devices with performances comparable to prototype single standing devices. The potential of the technology was further demonstrated by the fabrication and characterization of a fully integrated power detector circuit. The development of this process lays the foundation for the realization of fully integrated RF front-ends on flexible substrates. This work was presented at the 2023 Device Research Conference by Paula Palacios (oral, equal contribution) in Santa Barbara, CA, USA. A journal publication is currently in review. LB - PUB:(DE-HGF)11 DO - DOI:10.18154/RWTH-2025-00435 UR - https://publications.rwth-aachen.de/record/1002257 ER -