First Principle Analysis of Li-Doped Armchair Graphene Nanoribbons for Nanoscale Metal Interconnect Applications

In this paper, the effect of alkali metal, Li, as substitutional doping in armchair Graphene Nanoribbons (AGNRs) is investigated. Electronic and transport properties and structural stability of Li-doped AGNRs are investigated using density functional theory (DFT) and non-equilibrium Green's function (NEGF). First principle calculations have been performed on pristine (undoped), center Li-doped, one-edge Li- terminated and both-edge Li-terminated AGNRs. Our calculations reveal that all the structures analyzed are thermodynamically stable. Based on transmission spectrum and standard two-probe setup based I-V characteristics of all the considered configurations, center Li-doped AGNRs are found to be the most suitable candidate for on-chip interconnect applications. For center Li-doped AGNRs, kinetic inductance, L_k, and quantum capacitance, C_Q, are extracted as 12.51 nH/μm and 2.7 fF/μm, respectively, which results in nearly 7x, 2.5x and 1.1x higher current as compared to pristine, one-edge Li-terminated and both-edge Li-terminated AGNRs, respectively. We have also compared our results with center Fe-doped AGNRs, where center Li-doped AGNRs provide 1.71x higher current. Our study suggests about the substitutional doping of Li at the center in AGNRs make it an excellent metal that can be used in advanced nanoscale interconnect applications. In addition, this study can be extended towards the use of multiple layers of center Li-doped AGNRs in future that may further improve the interconnect performance.