Towards an accurate measurement of thermal contact resistance at chemical vapor deposition-grown graphene/SiO₂ interface through null point scanning thermal microscopy

In the development of graphene-based electronic devices, it is crucial to characterize the thermal contact resistance between the graphene and the substrate precisely. In this study, we demonstrate that the thermal contact resistance between CVD-grown graphene and SiO₂ substrate can be obtained by measuring the temperature drop occurring at the graphene/SiO₂ interface with null point scanning thermal microscopy (NP SThM), which profiles the temperature distribution quantitatively with nanoscale spatial resolution (∼50 nm) without the shortcomings of the conventional SThM. The thermal contact resistance between the CVD-grown graphene and SiO₂ substrate is measured as (1.7±0.27)×10^-6 m²K/W. This abnormally large thermal contact resistance seems to be caused by extrinsic factors such as ripples and metal-based contamination, which inevitably form in CVD-grown graphene during the production and transfer processes.