Browsing by Author "Huang, Yuefei"

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    First-Principles Study of Electron Transport Properties of Low-Dimensional Materials
    (2025-02-23) Huang, Yuefei; Yakobson, Boris I.
    Electron transport in low-dimensional materials is crucial for the development of advanced electronic devices and innovative applications in nanotechnology. This dissertation presents a first-principles calculation study of electron transport phenomena in three di↵erent nanoscale systems, each contributing to the frontier of nanoelectronics. DNA-inspired programmable self-assembly has been a paradigm for achieving ever more complex graphene-based nanostructures for novel electronic devices and applications. However, it is still unknown how hydrogen-bonded junctions inherent in such devices will perform as electron transport media. In the first part, we examine the electron transport properties of graphene nanoribbons (GNRs) connected by DNA nucleobases, utilizing first-principles Density Functional Theory (DFT) with the Non-Equilibrium Green’s Function (NEGF) method. Pronounced rectifying behavior and negative differential resistance are found, as well as high conductance in certain structures. The identified sensitivity of the current response to atomic details of the interfaces offers initial hints and guidance for experimental realization. The current response is found to be tunable by electrostatic doping, indicating the potential application of the junction as a nanoscale switch. The second part focuses on electron transport across lateral interfaces between graphene and borophene. By employing DFT+NEGF methods, we analyze the electron transmission and contact resistance in different borophene-graphene lateral junctions. We also present a rigorous method for extracting the contact resistance between bulk materials from quantum transport in the nanoscale. Borophene exhibits low contact resistance with graphene compared to other metals, due to the similarity in conducting orbitals. This indicate that borophene could be a good conductor in graphene based devices. In the third part, we discuss the atomistic processes responsible for the non-volatile resistance switching in a monolayer-thin memristor, also known as an “atomristor”. We demonstrate how the write, read, and retention performances of the atomristor depend on control parameters such as applied bias, choice of electrode materials, and device geometry. We map out the underlying energy landscape that governs the translocation kinetics of a single atom responsible for the atomristor operation. This allows us to prescribe a suitable metal-electrode material and provides a clear picture of the underlying processes in memristors at the 2D limit. Overall, this dissertation provides valuable insights into electron transport phenomena in low-dimensional materials, paving the way for their integration into nextgeneration electronic devices.