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oai:ubir.buffalo.edu:10477/794032025-10-01T22:52:30Zcom_10477_77914col_10477_79301

Terahertz Hybrid Graphene–Metal Reflectarrays Karmakar, Arka Einarsson, Erik Electrical Engineering electrical engineering materials science Ph.D. Graphene, which is a planar or 2D allotrope of carbon, is actually the building block of graphite. Graphene has potential applications in many fields, such as high frequency field-effect transistors, flexible electronics, touch panels, optoelectronic devices, energy storage devices, and wearable technology. Despite such promise,most of the graphene-based applications to date are limited to either theoretical work or laboratory research. This is due to the many challenges related to fabrication of graphene-based devices.Continuous graphene is a necessity for many electrical and optical applications.These applications, however, are built upon substrates that are not suitable for graphene growth. As a result, graphene must be transferred from its growth substrate (usually Cu foil) to a different substrate (such as a silicon wafer). Transfer techniques often introduce defects in graphene, such as wrinkles, cracks, and voidsor holes. To address this problem, we developed a wet graphene transfer method in which we add a copolymer to poly(methyl methacrylate) (PMMA) prior to transfer.Unlike previously reported wet methods, we show that adding a copolymer layer atop a PMMA layer before transfer improves graphene continuity by virtually eliminating cracks and holes. The result, as determined by quantitative image analysis, is 99.8% continuous graphene over a 1 cm × 1 cm area.In addition to its many unique electronic properties, graphene can sustain THz-frequency plasmons at room temperature. In an attempt to exploit this property for THz communication, we have demonstrated a hybrid graphene–metalreflectarray structure. In this reflectarray, the active elements are metal andgraphene reduces the reflected power by destroying the confinement. Lastly,we investigate all-graphene plasmonic antenna arrays, and propose an array of suspended graphene regions to realize plasmonic resonant cavities. 2019-04-04T20:32:28Z 2019-04-04T20:32:28Z 2019 2019-01-15 17:11:46 Text Dissertation http://hdl.handle.net/10477/79403 eng Users of works found in University at Buffalo Institutional Repository (UBIR) are responsible for identifying and contacting the copyright owner for permission to reuse. University at Buffalo Libraries do not manage rights for copyright-protected works and cannot assist with permissions. Copyright retained by author. application/pdf State University of New York at Buffalo