Transport studies in graphene-based materials and structures

Jiuning Hu, Purdue University

Abstract

Graphene, a single atomic layer of graphite, has emerged as one of the most attractive materials in recent years for its many unique and excellent properties, inviting a broad area of fundamental studies and applications. In this thesis, we present some theoretical/experimental studies about the thermal, electronic and thermoelectric transport properties in graphene-based systems. We employ the molecular dynamic simulations to study the thermal transport in graphene nanoribbons (GNRs) exhibiting various properties, including chirality dependent thermal conductivity, thermal rectification in asymmetric GNRs, defects and isotopic engineering of the thermal conductivity and negative differential thermal conductance (NDTC) at large temperature biases. We prove a theorem on the existence of NDTC in general one-dimensional diffusive thermal transport. We synthesis graphene composites and characterize their electric and thermal properties. Their electrical conductivity follows the percolation theory. We use 3-w method to measure the thermal conductivity and find that their thermal conductivities can be tuned by the graphene filler concentration. We build a micro-manipulator to accurately align and transfer two-dimensional materials, e.g., graphene and boron nitride (BN). We then fabricate the stacked BN/grapnene/BN/graphene/BN systems with isolated metal contacts to each graphene layer, to study the counterflow thermoelectric transport and Coulomb drag. In the last we present our theoretical considerations about the transport properties of multilayer systems with interlayer Coulomb interactions, using phenomenological arguments, Drude-like models and Boltzmann transport formalism, and discussed the potential for the interlayer interaction to enhance the thermoelectric figure of merit.

Degree

Ph.D.

Advisors

Chen, Purdue University.

Subject Area

Low Temperature Physics|Condensed matter physics|Materials science

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