Conductance growth in metallic bilayer graphene nanoribbons with disorder and contact scattering

By using a decomposition elimination method for Green's function matrix, we explore the effects of both disorder and contact scattering on electronic transport in metallic bilayer graphene nanoribbons (BGNRs) and related structures, in the limit of phase-coherent transport. Due to the inter-layer interaction, a conductance gap is observed at Fermi energy in primary metallic zigzag BGNRs. It is found that the fashion of the conductance variations with disorder depends strongly on the type of disorder and contact scattering. In the edge disordered BGNR, the conductance decreases monotonically with the disorder increasing and finally tends to disappear, while a nonmonotonic behavior is obtained in the single-layer disordered BGNR, first decreasing then increasing. In the presence of contact scattering, especially, an abnormal growth of the conductance appears at much lower disorder in both edge and single-layer disordered BGNRs, which may be due to the destruction of coherence by the introduction of disorder.