Purification/annealing of graphene with 100-MeV Ag ion irradiation
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NANO EXPRESS
Open Access
Purification/annealing of graphene with 100-MeV Ag ion irradiation Sunil Kumar1*, Ambuj Tripathi1, Fouran Singh1, Saif Ahmad Khan1, Vikas Baranwal2 and Devesh Kumar Avasthi1
Abstract Studies on interaction of graphene with radiation are important because of nanolithographic processes in graphene-based electronic devices and for space applications. Since the electronic properties of graphene are highly sensitive to the defects and number of layers in graphene sample, it is desirable to develop tools to engineer these two parameters. We report swift heavy ion (SHI) irradiation-induced annealing and purification effects in graphene films, similar to that observed in our studies on fullerenes and carbon nanotubes (CNTs). Raman studies after irradiation with 100-MeV Ag ions (fluences from 3 × 1010 to 1 × 1014 ions/cm2) show that the disorder parameter α, defined by ID/IG ratio, decreases at lower fluences but increases at higher fluences beyond 1 × 1012 ions/cm2. This indicates that SHI induces annealing effects at lower fluences. We also observe that the number of graphene layers is reduced at fluences higher than 1 × 1013 ions/cm2. Using inelastic thermal spike model calculations, we estimate a radius of 2.6 nm for ion track core surrounded by a halo extending up to 11.6 nm. The transient temperature above the melting point in the track core results in damage, whereas lower temperature in the track halo is responsible for annealing. The results suggest that SHI irradiation fluence may be used as one of the tools for defect annealing and manipulation of the number of graphene layers. Keywords: Graphene; Ion irradiation; Annealing; Disorder parameter; Inelastic thermal spike model PACS: 60.80.x; 81.05.ue
Background Graphene is a new member of the carbon family that has two-dimensional honeycomb lattice structure [1,2]. It is a basic building block for other carbon materials of different dimensionalities. It can be wrapped into zerodimensional fullerenes, rolled up into one-dimensional carbon nanotube and stacked together to form threedimensional graphite [3]. The high mechanical stability together with ballistic electron transport properties makes graphene a strong replacement for silicon-based semiconductor technology. At present, electron beam lithography (EBL) is widely used to fabricate nanoelectronic devices. For example, EBL is often adapted for fabrication of drain source and gate electrodes in graphene field-effect transistor (GFET) structure, while graphene channel is fabricated by alternate means. Similarly, the use of scanning electron microscope (SEM) for observation and testing of GFET * Correspondence: [email protected] 1 Materials Science Group, Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067, India Full list of author information is available at the end of the article
structures is very common [4]. Electron beam itself has also been used for the formation of epitaxial graphene on the surface of a 6H-SiC substrate by irradiation [5]. Hence, i
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