IEC TS 62607-6-24:2026

Nanomanufacturing - Key control characteristics - Part 6-24: Graphene-related products - Number of layers of graphene: optical contrast

IEC TS 62607-6-24:2026 which is a Technical Specification, establishes a standardized method to determine the key control characteristic (KCC)
• number of layer distribution
for CVD graphene film by
• optical contrast measurement
The number of layers and number of layer distribution of CVD graphene film is derived by G‑channel contrast values.
This method is applicable for clean CVD graphene film without twisted multilayer structures on a SiO2/Si substrate.

General Information

• Status: Published
• Publication Date: 28-Jun-2026
• ICS: 07.120 - Nanotechnologies
• Technical Committee: TC 113 - Nanotechnology for electrotechnical products and systems
• Drafting Committee: WG 8 - TC 113/WG 8
• Current Stage: PPUB - Publication issued
• Start Date: 29-Jun-2026
• Completion Date: 17-Jul-2026

Overview

IEC TS 62607-6-24:2026 - Nanomanufacturing - Key control characteristics - Part 6-24: Graphene-related products - Number of layers of graphene: optical contrast is a technical specification developed by the International Electrotechnical Commission (IEC). This standard establishes a globally applicable, standardized method for determining the key control characteristic-specifically, the number of layer distribution-for chemical vapor deposition (CVD) graphene films using optical contrast measurements. The methodology defined in this specification is intended for clean CVD graphene films, free of twisted multilayer structures, on SiO₂/Si substrates.

Monitoring and specifying the number of layers in graphene films is essential, as these features directly influence the electronic, mechanical, and optical properties of materials used in numerous advanced applications. The optical contrast method offers a reliable, efficient, and non-destructive means of characterizing layer distribution across large areas, supporting industrial-scale graphene manufacturing and quality control.

Key Topics

• Number of Layer Distribution: Specifies how to assess the distribution of mono- and multilayer domains within a CVD graphene film by analyzing optical contrast.
• Optical Contrast Measurement: Details a non-destructive technique using optical microscopy and digital imaging, focusing on the green channel (G-channel) value for high sensitivity to graphene layers.
• Measurement Procedure: Outlines steps including white balance calibration, sample preparation, optical imaging, data extraction from optical images, statistical analysis, and reporting results.
• Applicability: The method is tailored for clean, non-twisted CVD graphene films on standardized SiO₂/Si substrates.
• Data Analysis: Involves extracting G-channel contrast values from optical images, constructing statistical histograms, and determining area proportions for domains of different layer numbers.
• Reporting: Defines requirements for documenting test parameters, equipment details, optical images, contrast images, histograms, and comprehensive error analysis.

Applications

The standardized optical contrast method as defined by IEC TS 62607-6-24:2026 has broad relevance for various sectors within nanomanufacturing and graphene technology:

• Quality Control in Graphene Production: Enables efficient, non-destructive assessment of CVD graphene films' uniformity and layer distribution during large-scale manufacturing.
• R&D and Material Characterization: Supports researchers and developers in optimizing synthesis processes and evaluating fundamental material properties based on accurate layer characterization.
• Electronics and Optoelectronics: Ensures graphene films meet stringent criteria for next-generation electronic devices, sensors, transparent conductors, and optoelectronic components.
• Energy Storage and Conversion: Facilitates development of materials with tailored electrical and mechanical properties for use in batteries, supercapacitors, and fuel cells.
• Standardized Reporting and Compliance: Encourages harmonized documentation and traceability in the graphene industry, supporting regulatory compliance and international collaboration.

Related Standards

Professionals working with IEC TS 62607-6-24:2026 may find value in these related standards and references:

• IEC TS 62607-6-11:2022: Nanomanufacturing - Key control characteristics - Part 6-11: Graphene - Defect density: Raman spectroscopy. This standard outlines Raman spectroscopy techniques for quantifying defect density in graphene.
• ISO/TS 80004‑13:2024: Nanotechnologies - Vocabulary - Part 13: Graphene and other two-dimensional (2D) materials. Provides essential terminology for the field.
• Other Parts of IEC 62607 Series: Covering key control characteristics for carbon nanotubes, graphene and related nanomaterials.

By providing clarity and consistency in measurement and reporting, IEC TS 62607-6-24:2026 supports reliable quality assurance and fosters innovation in nanomanufacturing involving graphene and advanced 2D materials.

Standards Content (Sample)

IEC TS 62607-6-24 ®
Edition 1.0 2026-06
TECHNICAL
SPECIFICATION
Nanomanufacturing - Key control characteristics -
Part 6-24: Graphene-related products - Number of layers of graphene: optical
contrast
ICS 07.120  ISBN 978-2-8327-1338-9

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CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 General . 7
4.1 Measurement principle . 7
4.2 Description of measurement equipment . 8
4.3 Sample preparation . 8
5 Measurement procedure . 9
5.1 Establish the correlation between G-channel contrast value C and number
G
of layers . 9
5.2 White balance calibration . 9
5.3 Set up the digital camera . 9
5.4 Capture the optical image . 9
5.5 Obtain G-channel contrast images . 9
5.6 Determine the G-channel contrast values of the samples with known number

of layers . 9
6 Data analysis or interpretation of results . 10
7 Results to be reported . 10
Annex A (normative) Optical contrast values of samples with known number of layers . 12
Annex B (normative) Acquire the number of layer distribution of monolayer CVD
graphene . 14
Annex C (normative) Acquire the number of layer distribution of CVD graphene with
multilayer domains. 17
Annex D (informative) Transfer of CVD grown graphene films . 20
Bibliography . 21

Figure 1 – Schematics of the optical contrast method . 8
Figure A.1 – Optical image, Raman spectra and Raman G-band mapping of the
mechanically exfoliated graphene flake . 12
Figure A.2 – G-channel image of the exfoliated graphene flake extracted from the
optical image . 13
Figure A.3 – 3D G-channel contrast image of the exfoliated graphene flake with light
illumination corrections . 13
Figure B.1 – Optical image of the CVD monolayer graphene . 14
Figure B.2 – G-channel image of the CVD monolayer graphene extracted from the
optical image . 14
Figure B.3 – 3D G-channel contrast image of the CVD monolayer graphene with light
illumination corrections . 15
Figure B.4 – Histogram of the G-channel contrast values across the optical image . 15
Figure B.5 – Curve fitting of the G-channel contrast histogram . 15
Figure C.1 – Optical image of the CVD graphene films. 17
Figure C.2 – G-channel image of the CVD graphene films extracted from the optical
image . 17
Figure C.3 – 3D G-channel contrast image of the CVD graphene films with light
illumination corrections . 18
Figure C.4 – Histogram of the G-channel contrast values across the image . 18
Figure C.5 – Curve fitting of the G-channel optical contrast histogram . 18

Table 1 – The relationship between G-channel contrast values C and number of
G
layers. 9
Table 2 – The peak position of G-channel contrast value and area ratio . 10
Table A.1 – Relationship between reference C and number of layers . 13
G
Table B.1 – The peak position of G-channel contrast value and area ratio . 16
Table C.1 – The peak position of G-channel contrast value and layer ratio . 19

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Nanomanufacturing - Key control characteristics -
Part 6-24: Graphene-related products -
Number of layers of graphene: optical contrast

FOREWORD
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shall not be held responsible for identifying any or all such patent rights.
IEC TS 62607-6-24 has been prepared by IEC technical committee 113: Nanotechnology for
electrotechnical products and systems. It is a Technical Specification.
The text of this Technical Specification is based on the following documents:
Draft Report on voting
113/952/DTS 113/979/RVDTS
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this Technical Specification is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all parts of the IEC 62607 series, published under the general title Nanomanufacturing -
Key control characteristics, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
– reconfirmed,
– withdrawn, or
– revised.
INTRODUCTION
Graphene, as a pioneer of 2D materials, plays a critical role in many state-of-the-art applications,
extensively involving electronics, optoelectronics, sensors, and energy storage. [1] Graphene
has many desirable properties, e.g. high carrier mobility, broadband optical absorption,
biocompatibility and excellent stability and hence has good prospects not only for basic
research but also for various industrial applications. Large-area graphene film fabricated by
chemical vapour deposition (CVD) method is one of the most promising candidates for
commercialization. However, large-area CVD graphene films typically contain multilayer
domains that occupy varying proportions of the surface area, which can significantly affect their
electrical, mechanical and optical properties. Therefore, it is crucial to quantitatively assess
number of layer distribution (i.e. the area proportions for various layer domains) in CVD
graphene films for both research and application development.
There are many approaches for measuring number of layers of graphene films, such as
transmission electron microscopy (TEM), Raman spectroscopy, optical microscopy, and atomic
force microscopy (AFM). However, how to measure number of layer distribution is not specified
yet. This will affect application development and commercialization of large-area CVD graphene
film.
This document specifies a simple, high-throughput, and non-destructive approach to measure
number of layer distribution of large-area CVD graphene film by optical contrast method. The
basic principle and experimental approach of the optical contrast method are presented to
identify number of layer distribution. This method relies on the statistical analysis of the optical
contrast values of the pixels that make up the sample's optical images, and it is significantly
more efficient than TEM, AFM and Raman spectroscopy characterization method. With light
illumination corrections, the coverage ratio of monolayer and multilayer domains in large-scale
CVD graphene can be obtained accurately.

___________
Numbers in square brackets refer to the Bibliography.
1 Scope
This part of IEC 62607 establishes a standardized method to determine the key control
characteristic (KCC)
– number of layer distribution
for CVD graphene film by
– optical contrast measurement
The number of layers and number of layer distribution of CVD graphene film is derived by
G-channel contrast values.
This method is applicable for clean CVD graphene film without twisted multilayer structures on
a SiO /Si substrate.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC TS 62607-6-11:2022, Nanomanufacturing - Key control characteristics - Part 6-11:
Graphene - Defect density: Raman spectroscopy
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
– IEC Electropedia: available at https://www.electropedia.org/
– ISO Online browsing platform: available at https://www.iso.org/obp
3.1
optical contrast value
C
normalized difference in reflected light intensity between the blank substrate and the sample
on the substrate
II−
substrate sample
C=
(1)
I
substrate
where
is the reflected light intensity of the blank substrate;
I
substrate
I is the reflected light intensity of the sample on the substrate.
sample
3.2
G-channel value
value extracted from green channel (G-channel) at each pixel in the optical image
Note 1 to entry: The G-channel value is in the range 0 to 255.
3.3
G-channel contrast value
C
G
normalized difference in G-channel value between the blank substrate and the sample on the
substrate
GG−
substrate sample
C =
(2)
G
G
substrate
where
G and G are the G-channel values at each pixel taken from the substrate and
substrate sample
graphene film regions, respectively.
4 General
4.1 Measurement principle
Optical image of graphene film contains the information of reflected light. Graphene films with
different number of layers or different thicknesses exhibit different RGB channel values shown
in the optical images. [2] Particularly, for graphene film deposited on a 300 nm SiO2/Si substrate,
theoretical analysis and experimental results have demonstrated that among the RGB channels,
the G-channel value shows the largest variation with the increasing number of layers of
graphene film. [3] Hence, it is reasonable to define optical contrast value (Formula (1)) and use
G-channel contrast value (Formula (2)) as an indicator to identify the number of layers of
graphene film. The number of layer distr
...