Tuning the band gap of bilayer graphene by ion implantation: Insight from computational studies

By employing molecular dynamics (MD) simulations based on empirical potentials and density functional theory, we demonstrate that the electronic properties of bilayer graphene could be tailored by means of low-energy ion irradiations. We first performed MD simulations to investigate the doping and intercalation effect in bilayer graphene induced by low-energy B and N bombardment. Our simulation shows that there are two maximal probabilities for perfect substitution of a carbon atom with incident B or N, corresponding to the two layers. The highest substitutional probability is observed for N irradiation which is 38% at 70 eV in the upper layer and 33% at 110 eV in the lower layer. We have calculated the energy bands for all the atomic configurations that appear after the bombardment of B and N and show that the band gap of bilayer graphene can be widely tuned via the incorporation of B and N into the bilayer graphene. The maximal band gap is found to be 392.1 meV when the B implants into a graphene layer with the knocked C forms a C-C dumbbell defect in another layer. We also investigate the probability of Au intercalated into the bilayer graphene and show that up to 93% of incident Au can be trapped between the two layers when the incident energy is close to 90 eV, which gives rise to the n-type doping of graphene. The present results demonstrate that ion irradiation is an effective route to manipulate the structure of bilayer graphene and thus provide a way for controllable modification of its electronic properties for a variety of future nanoelectronic applications.