[13a-A32-1~9] 17.2 Graphene

▲ [13a-A32-8] Helium ion milling of HSQ covered graphene: Control of substrate swelling and imaging disorder

〇(P)Marek Edward Schmidt¹, Ahmed Hammam^1,2, Manoharan Muruganathan¹, Shinichi Ogawa³, Hiroshi Mizuta^1,4 (1.JAIST, 2.Minia Univ., 3.AIST, 4.Southampton Univ.)

Keywords:Graphene, Helium Ion Microscopy, GNR

Graphene is a zero band gap two dimensional (2D) material with superior electronic properties. However, opening a bandgap in graphene is essential for graphene-based electronic devices. Opening an energy gap (E_G) in graphene can be achieved by patterning the 2D graphene sheet into a narrow ribbon, called GNR. For a width smaller than 10 nm the E_G is more than 100 meV. Many techniques and methods have been developed to fabricate GNRs, however the most common technique remains to be electron beam lithography (EBL) patterning of an etch mask followed by reactive ion etching (RIE). Nevertheless, using the RIE method leads to a high degree of edge roughness in addition to the difficulty of achieving sub-10-nm widths. Here we propose a combination of EBL and helium ion microscopy (HIM) milling for sub-10-nm GNRs with smooth edges, where a ~80 nm wide RIE-patterned GNR is milled to the desired width using HIM (Figure 1a). The reason for using this two-step method is a reduction in required helium ion exposure time and thus elimination of the substrate swelling effect. We discuss the sample preparation, the milling process, and the results obtained.