Interfacing resistances in conducting probe atomic force microscopy with carbon nanotubes functionalised tips

A comparative study for the evaluation of carbon nanotube (CNT) functionalised tips as an interface for the determination of electrical and electronic properties of the surface of materials and devices is presented. The results of current spectroscopy measurements, complemented with force-current testing, reveal a strong dependence of the establishment of tip-sample electrical contact with environmental conditions and procedure. Multiwalled CNT-mediated measurements are compared with the results by commonly used as-purchased probes, metal-coated and Si probes, upon an inert and low-resistance Au substrate. The introduction of CNTs in the tip vicinity represents a drastic advance in the conduction capability as compared with the silicon probes. Despite a certain reduction of conduction as compared with metal-coated probes, a significant improvement of tip apex durability, together with, non-invasive mechanical contact to the sample is demonstrated. The present multiwalled CNT probes are proposed as an ideal element for electronic studies at the nanometre scale by atomic force microscopy.