First-principles analysis of transition metal doped and edge-passivated armchair grapheme nanoribbons for nanoscale interconnects

Abstract

Metallicity is a critical factor in determining a material's suitability for interconnect applications. In case of shrinkage in cross-sectional dimensions, interconnect performance is severely impacted. More than half of modern microprocessors' power is consumed by interconnects. One of the strongest candidates among various interconnect alternatives is Graphene. Despite its semi-metallic nature, it exhibits much more powerful electronic properties, such as mean free path and current-carrying capability in its pristine (undoped) state. Nanoribbon-shaped Graphene is required for nanoscale interconnections. Graphene nanoribbons (GNRs) encounter a non-zero bandgap upon formation, which poses one of the biggest challenges to its application in nanoscale interconnects. Hydrogen passivation is additionally used to prevent edge scattering by removing dangling bonds on the edges of the GNRs. The GNR's bandgap is further increased with this process. As a result, the majority of fabricated GNRs exhibit semiconducting behavior. Generally, semiconducting behavior is observed only in armchair GNRs. In light of this, AGNRs were chosen for the first-principles study. The metallicity of AGNRs must be improved before they can be used for nanoscale interconnects. This thesis proposes two approaches to solving the non-zero bandgap and higher resistance of monolayer AGNR. Substitutional doping with metal atoms is the first, while edge-passivation in monolayer AGNRs is the second approach. According to my study, transition metal atoms make a significant difference to the resistance of the proposed AGNRs when compared to pristine AGNRs when used in these two approaches. My study explores three distinct types of substitutional doping, including one-edge, both-edge and center doping. In AGNRs, edge passivation is achieved in one of the two ways: one-edge passivation or both-edge passivation. Any atom in the periodic table appears to behave very differently at two-dimensional scales. This means that even a small change in structure should be carefully examined. Throughout my study, Osmium (Os) has proven to be the best element for edge passivation and doping. Os-(Os-doped-AGNR)-Os possesses the greatest number of conduction channels and the highest current-carrying capability. This suggests that the proposed structure Os-(Os-doped-AGNR)-Os will be a viable candidate for future interconnect applications.