Dependence of transport on adatom location for armchair-edge graphene nanoribbons

TL;DR

This paper investigates how the position of an adatom affects electron transport in armchair-edge graphene nanoribbons, revealing that adatom location can induce semiconducting behavior in metallic ribbons, which is useful for characterization.

Contribution

It demonstrates the dependence of tunneling current on adatom position and ribbon width using nonequilibrium Green's function, highlighting a method to control electronic properties in graphene nanoribbons.

Findings

Adatom position significantly influences tunneling current.

Certain adatom locations induce a transmission gap in metallic AGNRs.

The results suggest potential for nanoscale electronic device control.

Abstract

We study the transport property for armchair-edge graphene nanoribbons (AGNRs) with an adatom coupling to a semi-infinite quantum wire. Using the nonequilibrium Green's function approach with tight-binding approximation, we demonstrate that the tunneling current through the system is sensitively dependent on both the AGNR width and adatom location. Interestingly, when the adatom locates onto a carbon atom in the 3$j$th chain from the edge of a metallic AGNR, the system shows a transmission gap accompanied by a threshold voltage in $I-V$ curve like a semiconducting AGNR. This effect may be useful in scanning tunneling microscopy experimental characterization on graphene samples.