IEC TS 62607-6-8:2023 establishes a method to determine the key control characteristic sheet resistance RS [measured in ohm per square (Ω/sq)], by the in-line four-point probe method, 4PP.
The sheet resistance RS is derived by measurements of four-terminal electrical resistance performed on four electrodes placed on the surface of the planar sample.
The measurement range for RS of the graphene samples with the method described in this document goes from 10−2 Ω/sq to 104 Ω/sq.
The method is applicable for CVD graphene provided it is transferred to quartz substrates or other insulating materials (quartz, SiO2 on Si, as well as graphene grown from silicon carbide.
The method is complementary to the van der Pauw method (IEC 62607-6-7) for what concerns the measurement of the sheet resistance and can be useful when it is not possible to reliably place contacts on the sample boundary.