Direct growth of single carbon nanofiber onto tip of scanning probe microscopy induced by ion irradiation

A novel method for the direct growth of a single carbon nanofiber (CNF) onto the tip of a commercially available scanning probe microscope (SPM) using Ar⁺-ion irradiation was demonstrated. This method was proposed on the basis of the experimental fact that the Ar⁺ ion bombardment of carbon coated substrates induced the formation of conical protrusions that possessed a single CNF at their tip. Commercially available Si SPM tips were coated with carbon and then were Ar⁺-ion bombarded at room temperature and at 200°C. On the ion-bombarded SPM tips, single CNFs of about 30 nm in diameter grew. Their length, which was controlled by varying the sputtering duration, was typically 0.5-1.5 μm. Using the CNF-tipped probes thus prepared, clear atomic force microscope (AFM) images with a high spatial resolution were attained for Si-grating samples. No deterioration in the spatial resolution was detected after repeated scans for 90 min. Thus, the ion-irradiation method was concluded to be quite promising for the fabrication of practical CNF-tipped SPM probes.