Two-dimensional materials for novel electronic applications: The graphene mixer and TaS2 hyper-FET.

摘要

iii Abstract First successfully isolated in 2004, graphene is a two-dimensional crystal comprised of a one-atom thick layer of carbon atoms arranged in a honeycomb lattice. Initial demonstrations of the exceptional material and electronic properties of graphene sparked a period of accelerated research and investigation into two-dimensional material systems and the unique properties they offer. During this period, there have been continuous breakthroughs with regard to isolation, growth, and characterization of two-dimensional systems, enabling the number of known two-dimensional and layered materials to rapidly expand. As the number of two-dimensional and layered material systems investigated increases, so too does the number of potential applications. Currently, there exist several fundamental questions as to the role these materials might play in future electronic applications. As an example, graphene has been suggested for use as the channel material in high frequency transistors due to its exceptionally high carrier mobility, but also as an interconnect for integrated circuits due to its excellent thermal properties and ability to support very high current densities. Furthermore, there exist several fundamental challenges to implementing graphene and other two dimensional materials in many of the proposed applications. For the case of graphene this includes high contact resistivities and the inability to control edge morphology in highly scaled geometries.;This dissertation focuses specifically on the two-dimensional materials of graphene and tantalum di-sulfide in an attempt to elucidate some of the potential applications and challenges facing these two materials. It addresses several issues related to the development of a graphene based transistor for use in high frequency applications and the optimization of the graphene based transistor for mixing applications, including an analysis of graphene mixer design and the use of graphene nano-ribbon geometries to mitigate contact effects in highly scaled devices. In the final portion of the dissertation, the layered two-dimensional material 1T-TaS2 is explored for potential applications in electronics, where use of its insulator-metaltransition could be utilized to implement a steep-slope transistor in order to overcome conventional constraints which currently limit performance of highly scaled silicon transistors.