Edge-dependent ballistic transport through copper-decorated carbon-nanotube-graphene covalent junction with low Schottky barrier

Abstract

The ultrahigh carrier mobility and matchable work function of graphene have positioned this material as a leading candidate for the ideal contact material for carbon nanotubes (CNTs). Highly efficient carrier transport through CNT-graphene junctions is facilitated by covalently bonded contacts. This paper, therefore, proposes covalently bonded CNT-graphene junctions and investigates their characteristics theoretically. In these junctions, partially unzipped CNTs are longitudinally or radially bonded with graphene. By exploiting nonequilibrium Green's functions with density-functional theory, we examine ballistic electron transport (∼1.38 × 105 cm2/V s) and edge-dependent transport. Moreover, the contact properties of the junctions with adsorbed Cu atoms are investigated. Electron transfer from Cu to the junction turns the p-type Schottky contact into an n-type contact and decreases the Schottky barrier height from 0.2 to 0.08 eV. Furthermore, the junction resistance decreases by one to three orders of magnitude. The proposed design of Cu-decorated CNT-graphene junctions and first-principles calculations suggest an approach for low-power, high-performance CNT-based electronics.