Etch-less micropatterned epitaxial graphene via 2D and 3D site-selective growth

Francesca Iacopi, University of Technology Sydney

It is well known that harnessing graphene’s properties on a silicon platform could deliver a broad range of novel miniaturized and reconfigurable functionalities. Over the last decade, we have developed an epitaxial graphene on silicon carbide on silicon technology, using cubic SiC as a solid-state carbon source and template, and catalyzed with a Ni/Cu alloy [1]. The graphene growth via cupronickel allows for a liquid-phase epitaxial growth of graphene at a relatively low temperature of 1100ºC, allowing to mitigate the strong limitations posed by the very defective hetero-epitaxial SiC template.

We have recently confirmed the hallmarks of this epitaxial growth and its mechanisms with operando neutron reflectometry measurements conducted with the Spatz time-of-flight instrument at ANSTO [2]. This platform enables the fabrication of any complex graphene 2D or 3D pattern in a site – selective fashion, ie without chemical or physical etching of the graphene, at the wafer -scale and with sufficient adhesion for integration. Thanks to the solid-source approach, when the SiC is prepatterned on the silicon substrate, the graphene will only grow conformally around the SiC patterned walls to form graphene- coated 3D micro/nanostructures [3].

This approach is ideal for some key functionalities for MEMS/NEMS, nano-optics and metasurfaces that can be uniquely unlocked by the combination of graphene and silicon carbide [4, 5]. For applications where a flat/2D pattern of graphene is preferred, a complementary approach can be followed by prepatterning the cupronickel alloy instead via optimized lift-off processes, prior to the graphene growth [6]. The versatility of the cupronickel epitaxial graphene technology allows hence for a wide variety of wafer -scale fabrication on silicon, avoiding potentially detrimental chemical and physical etching of the graphene. We will highlight the learnings from the development of this technology and some of its most promising applications in the More-than-Moore domain.

1. N.Mishra et al, Journal of Physics D: Applied Physics 50 (9), 095302, 2017
2. A.Pradeepkumar, D.Cortie, E.Smyth, A.P. Le Brun, and F.Iacopi, in preparation, Nov 2023
3. B.Cunning et al, Nanotechnology 25 (32), 325301, 2014
4. E.Romero et al, Physical Review Applied 13 (4), 044007, 2020
5. P.Rufangura e al, Journal of Physics: Materials 3 (3), 032005, 2020
6. D.Katzmarek, A.Mancini, S.A.Maier and F.Iacopi, Nanotechnology 34 (40), 405302, 2023