Standards Development

Scope

This document details the methods for characterising the structural properties of CVD -grown graphene. The methods used are optical microscopy, Raman spectroscopy and transmission electron microscopy ( TEM). The properties determined are the percentage of substrate coverage of graphene, number of layers, the level of disorder and layer stacking. Sample preparation routines, measurement protocols and data analysis for the characterisation of CVD-grown graphene are provided.

Purpose

Graphene is predicted to impact many different appli cation areas such as solar cells, biosensors, displays, composites, flexible electronics and energy storage due to its exceptional properties. As industry uptake on this material increases, international standardization is critical to enable commercializat ion. Reliable, accurate, and reproducible measurements are important due to many production routes and producers of the material, in order to enable comparability and maintain high quality manufacture.

There are, in general, two forms of commercially -available graphene, namely flakes/particles or a sheet on a substrate. The former are supplied in the form of a powder or liquid dispersion and are typically flake -like in nature but may vary in lateral size and thickness, thus also containing flakes classed as graphite. The structural characterisation of these materials is described in ISO TS21356 -1:2021 Nanotechnologies — Structural characterization of graphene —Part 1: Graphene from powders and dispersions.

This document, the second part of 21356, describes t he structural characterisation of sheet-like graphene, predominantly produced via chemical vapour deposition (CVD). It details the methods for characterising the structural properties of CVD-grown graphene in a systematic way. The methods used are optical microscopy, Raman spectroscopy and transmission electron microscopy (TEM). The properties determined are the percentage of substrate coverage of graphene, number of layers, the level of disorder and layer stacking. For each technique, sample preparation routines, measurement protocols and ways to analyse the data are provided.