Formation of graphene nanoribbons and Y-junctions by hydrogen induced anisotropic etching

Abstract

Metal nanoparticles and H 2 induced etching of graphene are of significant interest to synthesis graphene nanoribbons and various other structures with crystallographically defined edges. Here, we demonstrate a controllable H 2 -induced etching process of graphene crystals to fabricate nanoribbons, and Y-junctions structures with pronounced edges. Individual graphene crystals and a continuous films were grown on Cu foil by solid source chemical vapor deposition (CVD) technique. The etching behavior of the synthesized graphene was investigated by annealing at 1000 0 C in a gas mixture of H 2 and Ar. A highly anisotropic etching creates hexagonal holes, nanoribbons and Y-junction graphene with clear edge structures. The distinct graphene edges of individual ribbon create 120° to form a Y-shape structure. The finding can be significant to fabricate well-defined graphene structures with controlled edges for electronic device applications as well as creating in-plane heterostructures with other two dimensional (2D) materials.obtain graphene with regular, zigzag or armchair edge structures. 26,28 In this prospect, exploring the anisotropic etching behavior of high quality CVD graphene is of great interest to fabricate nanoribbons with distinct edge structure. 29 Creating holes with defined edge structure also provide a platform to fabricate in-plane heterostructure with other 2D materials. Anisotropic etching of graphene basal plane has been explored with metal catalytic nanoparticles in presence of H 2 , selective oxidation, and water vapor at an elevated temperature. [30][31][32][33][34] Recently, anisotropic behavior of H 2 in the formation of graphene domains has been also observed, thereby obtaining pentagonal graphene domains with anisotropic growth and etching process. 35 Highly anisotropy etching of graphene can be achieved owing to significant differences in chemical reactivity of the zigzag and armchair edges. This has open new opportunities to control the structure of high quality exfoliated and CVD graphene in large-area for device integration. Again, fabrication of Y-shaped graphene nanoribbons with well-ordered edges can be significant, which is not yet addressed considerably. Theoretical analysis predicted specific properties of the Y-shaped zigzag graphene nanoribbons structure. [36][37][38][39][40] Formation of Y-shaped graphene nanoribbons by anisotropic etching process will enable to fabricate multi-terminal graphene-based nanoelectronic and spintronic devices. 41,42 However, synthesis of Y-shaped graphene nanoribbons with clear edges is significant area of graphene on Cu foil. Figure 5(b) shows formation of Y-shape graphene ribbons structure with edge etching from different directions. The perfect edges of individual ribbon create 120° to form an Y-shape structure. Previously, significant efforts have been made to synthesis Y-shape CNTs owing to its unique electrical properties. 45 The three-terminal Y-junction nanotubes exhibits the gating behavior, characteristic of transistors. Similarly, Y-junct...

Structure dependent hydrogen induced etching features of graphene crystals

“…29 Very recently, we have demonstrated nanoribbons and Y-shaped junctions fabrication by H 2 induced anisotropic etching. 24 The graphene nanoribbons with armchair edges possess a band gap changing with the width of ribbons, while zigzag edges shows magnetically ordered edge states. [30][31][32][33] These features of nanoribbons only can be observed with very regular and pronounced edge structures.…”

“…13,19-21 H 2 induced etching of graphene is a fascinating tool to fabricate nanoribbons, hexagonal holes, Y-shaped junctions, and other nanostructures with control edges. [22][23][24] Anisotropic etching behavior of graphene has been explored with metal nanoparticles in presence of H 2 , oxidation, and introduction of water vapor at high temperature annealing. [25][26][27][28] Hexagonal holes were created with welldefined edges by the etching process for fabrication of inplane heterostructure with hexagonal boron nitride (h-BN).…”

Generation of fully spin-polarized currents in three-terminal graphene-based transistors

“…Although the device fabrication and experimental measurement of spin currents in the well-defined zigzag edges are important challenges in this type of junctions, the Yshaped nanoribbons 38 with zigzag edges and Y-junction carbon nanotubes 39 with magnetic impurity may be experimentally useful for testing fully spin-polarized currents in such spin transistors.…”

Graphene Etching: How Could It Be Etched?

“…4a) [27], or H 2 etching during CVD graphene growth ( Fig. 4b-e) [28], or thermally activated Fe nanoparticles (Fig. 4f, g) [29].…”

“…To do this, the etching technology shows the great ability and gets the interests of the scientists and researchers in academy and industry through the world [20][21][22][23][24][25][26][27][28][29]. Several new methods have found out (i) plasma (inductively coupled plasma (ICP)), neutral beam assisted atomic layer etching (ALE), ion beam ICP, the reactive ion etching (RIE)) [20][21][22][23][24][25][26][27], (ii) the chemical vapor deposition (CVD) [28], or (iii) thermally activated Fe nanoparticles [29]. Plasma technology has been used to etch fine features in Si integrated circuits in the last four decades [20].…”