Confocal Raman spectromicroscopy of graphene

Confocal Raman spectromicroscopy is becoming an essential tool in the location and characterisation of 2D and nano-structured materials. Here spectral fingerprints and the ratios of peaks within a Raman spectrum are often used to confirm the presence of a materials and its dimensionality. For example, the number of layers of carbon materials are indicated through the observed 2D/G band ratio. However, large variation in data currently exists for graphene and this variability can lead to material mischaracterisation, ultimately resulting in unpredictable properties and irreproducible performance when these materials are incorporated into devices. In this manuscript, we report an investigation into aspects of confocal Raman microscopy and identify microscope features, such as chromatic aberrations, that may contribute to the variability in properties used in the characterisation of 2D materials. We also provide protocols for ensuring that materials are accurately characterised to enable better translation of 2D materials into devices. • Mischaracterisation of carbon materials is problematic for applications. • Spectromicroscopy is essential in characterising 2D materials, like graphene. • The confocal microscopy setup can impact the characterisation of carbon materials. • We detail methods for accurate and repeatable 2D material characterization.