Argon Cluster and Graphene Collision Simulation Experiment

Argon Cluster and Graphene Collision Simulation Experiment Formation of Nanopore in a Suspended Graphene Sheet with Argon Cluster Bombardment: A Molecular Dynamics Simulation study Abstract: Formation of a nanopore in a suspended graphene sheet using an argon gas beam was simulated using molecular dynamics (MD) method. The Lennard-Jones (LJ) two-body potential and Tersoff–Brenner empirical potential energy function are applied in the MD simulations for different interactions between particles. The simulation results demonstrated that the incident energy and cluster size played a crucial role in the collisions. Simulation results for the Ar55 –graphene collisions show that the Ar55 cluster bounces back when the incident energy is less than 11ev/atom, the argon cluster penetrates when the incident energy is greater than 14 ev/atom. The two threshold incident energies, i.e. threshold incident energy of defect formation in graphene and threshold energy of penetration argon cluster were observed in the simulation. The threshold ene rgies were found to have relatively weak negative power law dependence on the cluster size. The number of sputtered carbon atoms is obtained as a function of the kinetic energy of the cluster. Keywords: Nanopore, Suspended graphene sheet, Argon cluster, Molecular dynamics simulation Introduction The carbon atoms in graphene condense in a honeycomb lattice due to sp 2-hybridized carbon bond in two dimensions [1]. It has unique mechanical [2], thermal [3-4], electronic [5], optical [6], and transport properties [7], which leads to its huge potential applications in nanoelectronic and energy science [8]. One of the key obstacles of pristine graphene in nanoelectronics is the absence of band gap [9-10]. Theoretical studies have shown that chemical doping of graphene with foreign atoms can modulate the electronic band structure of graphene and lead to the metal to semiconductor transition and break the polarized transport degeneracy [11-12]. Also, computational studies have demonstr ated that some vacancies of carbon atoms within the graphene plane could induce a band-gap opening and Fermi level shifting [13-14]. Graphene nanopores can have potential applications in various technologies, such as DNA sequencing, gas separation, and single-molecule analysis [15-16]. Generating sub-nanometer pores with precisely-controlled sizes is the key difficulty in the design of a graphene nanopore device. Several method have been employed to punch nanopores in graphene sheets, including electron beam from a transmission electron microscope (TEM) and heavy ion irradiation. Using electron beam technique, Fischbein et al.[17] drilled nanopores with the width of several nanometers and demonstrated that porous graphene is very stable; but, this method cannot be widely used because of its low efficiency and high cost. Russo et al. [18] used energetic ion exposure technique to create nanopores with radius as small as 3Å. S. Zhao et al. [19] indicated that energetic cluster irra diation was more effective in generating nanopores in graphene, because their much larger kinetic energy could be transferred to the target atoms. Recent experimental works have further confirmed that cluster irradiation is a feasible and promising way in the generation of nanopores [20]. Numerical simulations have demonstrated that, by choosing a suitable cluster species and controlling its energy, a nanopores of desired sizes and qualities can be fabricated in a graphene sheet [19].