CVD Synthesis of Graphene Nanomesh on Ge(001)

Abstract

Bottom-up synthesis of functional graphene nanostructures on industry-compatible semiconductors such as Si and Ge is the key to unlocking the tremendous potential of graphene in electronic applications. Herein, we demonstrate the growth of graphene nanomesh on Ge using chemical vapor deposition – a technique used widely in the semiconductor industry. Graphene nanomesh is a promsing material in semiconductor electronics because of its ability to simultaneously achieve a large drive current and on/off ratio – one of the key challenges in graphene nanoribbon electronics[1]. However, in order to realize a nanomesh with desired and tunable electrical characteristics – an accurate control over the nanoribbon width, presence of atomically smooth edges, and nanoribbon placement is desired. In the literature, several techniques have been demonstrated to fabricate graphene nanomesh such as top-down lithography[2], bottom-up polymerization[3], and molecule-assisted CVD[4]; yet, a combination of accurate placement, tunable widths and atomically smooth edges has been challenging to achieve. We attempt to overcome this bottleneck by initiating CVD nanoribbon synthesis from deterministically placed arrays of graphene nanoseeds on Ge. We are able to tune the nanoribbon widths by changing the starting seed size and array pitch. The nanoribbons evolved from these nanoseeds fuse into each other when grown long enough – forming a nanomesh. These nanomeshes have atomically smooth edges and exhibit semiconducting characteristics. We also perform extensive simulations to identify the seed-sizes and pitches and demonstrate that this technique allows us to synthesize nanomeshes of desired architecture and electrical characteristics and thus can be used as channel materials in high performance / RF applications as well as BEOL interconnects. References Saraswat et al. ACS Nano, 15,3674-3708 (2021)Bai et al. Nature Nanotechnology, 5, 190–194 (2010)Moreno et al. Science, 360, 199-203 (2018)Kim et al. ACS Applied Materials & Interfaces, 13, 28593-28599 (2021)