3D arrangement of epitaxial graphene conformally grown on porousified crystalline SiC

TL;DR

This paper reports the first successful three-dimensional growth of high-quality epitaxial graphene on porousified crystalline SiC, opening new avenues for applications in sensing, energy, and catalysis due to its unique porous structure.

Contribution

It introduces a novel method for growing uniform, high-quality epitaxial graphene inside nanoporous SiC, combining advanced porosification and ultra high vacuum growth techniques.

Findings

Pore diameter of 180 nm confirmed by electron tomography

High-quality graphene with 2D/G ratio >1 verified by Raman spectroscopy

Uniform graphene coverage across the porous SiC surface

Abstract

Nanoporous materials represent a versatile solution for a number of applications ranging from sensing, energy applications, catalysis, drug delivery, and many others. The synergy between the outstanding properties of graphene with a three-dimensional porous structure, circumventing the limits of its 2D nature, constitutes therefore a breakthrough for many fields. We report the first three-dimensional growth of epitaxial graphene on a porousified crystalline 4H-SiC(0001). The wafer porosification is performed via a sequence of metal-assisted photochemical and photoelectrochemical etching in hydrofluoric acid based electrolytes. Pore dimensions of the matrix have been evaluated by electron tomography resulting in an average diameter of 180 nm. Graphene growth is performed in an ultra high vacuum environment at a base pressure of $10^{-11}$ mbar. The graphene growth inside the pores is uniform as confirmed by Transmission Electron Microscopy (TEM) analysis. Raman spectroscopy confirms the high quality of the graphene with a 2D/G ratio $>1$ and an average graphene crystal size of $\approx$ 100 nm. Furthermore, it demonstrates a uniform coverage of graphene across the whole sample area. The surface-to-volume ratio of this novel material, its properties, the tunability of the pore size and the scalability of the surface porosification process offer a game changing perspective for a large number of applications.