No abstract

The Si(0001) face and C(000-1) face dependences on growth pressure of epitaxial graphene (EG) grown on 4H-SiC substrates by ethene chemical vapor deposition (CVD) was studied using atomic force microscopy (AFM) and micro-Raman spectroscopy (μ-Raman). AFM revealed that EGs on Si-faced substrates had clear stepped morphologies due to surface step bunching. However, This EG formation did not occur on C-faced substrates. It was shown by μ-Raman that the properties of EG on both polar faces were different. EGs on Si-faced substrates were relatively thinner and more uniform than on C-faced substrates at low growth pressure. On the other hand, D band related defects always appeared in EGs on Si-faced substrates, but they did not appear in EG on C-faced substrate at an appropriate growth pressure. This was due to the μ-Raman covering the step edges when measurements were performed on Si-faced substrates. The results of this study are useful for optimized growth of EG on polar surfaces of SiC substrates.

Facile utilization of polyethylene (PE) film as both the supporting material for graphene transfer from copper foil and the target substrate for flexible strain sensor preparation in a single route.

Ordered graphene ribbons were grown on the surface of 4° off-axis 4H-SiC wafers by sublimation epitaxy, and characterized by using scanning electron microscopy (SEM), atomic force microscopy (AFM) and micro-Raman spectroscopy (μ-Raman). SEM showed that there were gray and dark ribbons on the substrate surface, and AFM further revealed that these ordered graphene ribbons had clear stepped morphologies due to surface step-bunching. It was shown by μ-Raman that the numbers of graphene layers of these two types of regions were different. The gray region was composed of mono- or bilayer ordered graphene ribbon, while the dark region was of tri- or few-layer ribbon. Meanwhile, ribbons were all homogeneous and had a width up to 40 μm and a length up to 1000 μm, without micro defects such as grain boundaries, ridges, or mono- and few-layer graphene mixtures. The results of this study are useful for optimized growth of high-quality graphene film on silicon carbide crystal.