Synthesis of Layer‐Tunable Graphene: A Combined Kinetic Implantation and Thermal Ejection Approach

Abstract

wileyonlinelibrary.comstructure and extraordinary physical properties. [1][2][3][4] To realize the potential of graphene in nanoelectronic devices, a uniform graphene layer with a well-controlled layer number should be synthesized fi rst because most of the physicochemical properties of graphene are sensitive to its thickness. For example, monolayer graphene has a zero band gap, whereas Bernal-stacked (AB-stacked) bilayer graphene is of signifi cant interest for graphene-based fi eld-effect transistors (FETs) and tunable laser diodes, [5][6][7] because of the feasibility to continuously tune up its band gap to 250 mV by applying a perpendicular electric fi eld. However, precise control of the thickness of graphene remains a major challenge. For the carbon-soluble materials (e.g., Ni, [ 8 ] Co, [ 9 ] Ru, [ 10 ] Pd, [ 11 ] and Mo [ 12 ] ), the chemical vapor deposition (CVD) synthesis of graphene proceeds via surface segregation followed by precipitation. Since the precipitation process is nonequilibrium, it is extremely challenging to tune the layer number of graphene using carbon-soluble metals in theory, though several approaches have attempted by reducing metal fi lm thickness Layer-tunable graphene has attracted broad interest for its potentials in nanoelectronics applications. However, synthesis of layer-tunable graphene by using traditional chemical vapor deposition method still remains a great challenge due to the complex experimental parameters and the carbon precipitation process. Herein, by performing ion implantation into a Ni/Cu bilayer substrate, the number of graphene layers, especially single or double layer, can be controlled precisely by adjusting the carbon ion implant fl uence. The growth mechanism of the layer-tunable graphene is revealed by monitoring the growth process, it is observed that the entire implanted carbon atoms can be expelled toward the substrate surface and thus graphene with designed layer number can be obtained. Such a growth mechanism is further confi rmed by theoretical calculations. The proposed approach for the synthesis of layer-tunable graphene offers more fl exibility in the experimental conditions. Being a core technology in microelectronics processing, ion implantation can be readily implemented in production lines and is expected to expedite the application of graphene to nanoelectronics.

Fast Batch Production of High-Quality Graphene Films in a Sealed Thermal Molecular Movement System

“…On the other hand, the production of H 2 can, in turn, balance the dehydrogenation of CH 4 . A previous experiment demonstrated that the growth of single graphene in square centimeter needs only 4 × 10 15 atoms, which are estimated to be 1.5 × 10 −4 mL of CH 4 gas . In our SAPCVD system, even though we introduce 1–16 mL CH 4 , far greater than the monolayer graphene growth needs, we can still obtain a uniform single layer in a broad single‐layer window.…”

A Review of Recent Applications of Ion Beam Techniques on Nanomaterial Surface Modification: Design of Nanostructures and Energy Harvesting

“…Carles et al researched the surface‐enhanced raman scattering (SERS) of Ag NP‐embedded substrates . Recently, some researchers have utilized C ion implantation to fabricate graphene on different substrates . Lee et al fabricated large‐scale graphene on Cu foils by ion implantation and subsequent annealing .…”

“…Also, Dharmaraj et al directly grew few‐layer graphene on a SiO 2 substrate by low‐energy carbon ion implantation . Furthermore, Wang et al reported that the number of graphene layers can be controlled by modulating the implantation dosage . Figure shows the Raman spectra and scanning tunneling microscopy (STM) topographical images of monolayer and bilayer graphene synthesized by ion implantation.…”

Spin-filter and negative differential resistance effect in zigzag-edged bilayer graphene nanoribbon devices

“…18,19 Therefore, bilayer graphene has been studied extensively, and has been proved having multiple applications in nanoelectronic devices. 20,21 Moreover, with the advance of experimental techniques, the layer-tunable graphene is coming true in a recent research, 22 which makes the synthesis of bilayer graphene easier in experiment. Thus, in order to investigate the spintronic devices based on bilayer graphene, it is very important to investigate the spin-dependent transport behaviours of zigzag-edged bilayer graphene nanoribbons (ZBGNRs).…”