Overview
IEC TS 62607-6-5:2022 - Nanomanufacturing: Graphene-based materials - Contact resistance and sheet resistance: transmission line measurement (TLM) - defines a standardized, reproducible method to determine contact resistance and sheet resistance of graphene and other two-dimensional (2D) materials using the transmission line measurement. The technique uses photolithographically defined test structures with multiple metal electrodes at increasing spacings; voltage drops between electrode pairs are used to extract sheet and contact resistances. The method is applicable to any 2D material with metal contacts on top, provided the metal–material interface is ohmic.
Key topics and technical requirements
- Measurement principle: Transmission line measurement (TLM) patterns comprising sequential metal contacts with varied spacing; analysis of measured voltage/current to separate sheet resistance and contact resistance.
- Test structures: Photolithographic electrode patterns (rectangular channels, 2-point and 4-point probe TLM geometries) formed on the 2D material.
- Sample preparation: Recommended procedures for device fabrication and contact formation to ensure reliable, ohmic electrical contact.
- Measurement procedures: Recommended I–V testing workflows, suggested two‑point and four‑point probe implementations, and guidance on ensuring linear (ohmic) behavior.
- Limitations and constraints: Notes on non‑ohmic (Schottky) contacts and when TLM results may be invalid or require alternative interpretation.
- Reporting and case studies: Required result formats, example datasets for graphene and MoS2, and comparison of TLM with conventional four‑point probe approaches.
- Ancillary content: Recommended measurement equipment, apparatus, and simulations supporting reproducibility and interpretation.
Applications and users
Practical applications include:
- Quality control and process monitoring for graphene and 2D‑material manufacturing
- Electrical characterization during R&D of sensors, flexible electronics, interconnects, and optoelectronic devices
- Metrology and verification in academic and industrial research labs
- Supplier qualification and incoming inspection of 2D material films
Typical users:
- Materials scientists and device engineers
- Process engineers in fabs and pilot lines
- Metrology labs and standards bodies
- Test & validation teams for 2D-material-based products
Benefits
- Provides a standardized, repeatable protocol for separating contact and sheet resistances without requiring film thickness in calculations
- Promotes consistent reporting and comparability across labs and manufacturers
- Enhances traceability in nanomanufacturing workflows for 2D materials
Related standards
- Part of the IEC TS 62607 series (Nanomanufacturing - Key control characteristics). This document is intended to be compatible with other performance standards in the series and with broader IEC metrology guidance for electrical characterization of nanomaterials.
Keywords: IEC TS 62607-6-5:2022, transmission line measurement, TLM, graphene, sheet resistance, contact resistance, two-dimensional materials, nanomanufacturing, ohmic contact.