Study of epitaxial graphene on non-polar 6H-SiC faces

TL;DR

This study compares epitaxial graphene growth on non-polar and polar 6H-SiC faces, revealing differences in morphology, disorder, and growth mechanisms influenced by surface properties and temperature effects.

Contribution

It provides new insights into how non-polar SiC faces affect graphene growth, morphology, and Raman characteristics compared to polar faces.

Findings

Non-polar faces show nanocrystalline graphite features, polar faces show step-like features.

Non-polar faces exhibit greater disorder and a red shift in Raman peaks with temperature.

Differences in morphology, thickness, and Raman signals between a-plane and m-plane EG.

Abstract

We present epitaxial graphene (EG) growth on non-polar a-plane and m-plane 6H-SiC faces where material characterization is compared with that known for EG grown on polar faces. Atomic force microscopy (AFM) surface morphology exhibits nanocrystalline graphite like features for non-polar faces, while the polar silicon face shows step like features. This differing behavior is attributed to the lack of a hexagonal template on the non-polar faces. Non-polar faces also exhibit greater disorder and red shift of all Raman peaks (D, G and 2D) with increasing temperature. This is attributed to decreasing stress with increasing temperature. These variations provide evidence of different EG growth mechanisms on non-polar and polar faces, likely due to differences in surface free energy. We also present differences between a-plane EG and m-plane EG in terms of morphology, thickness and Raman characteristics