The effect of the shape of a tip's apex on the fabrication of an AFM tip with an attached single carbon nanotube

We show how the shape of the apex on the tip of an atomic force microscope (AFM) affects the fabrication of a tip with an attached single multi-walled carbon nanotube (MWNT). To make an MWNT-attached AFM tip, we dropped a drop of MWNT solution onto the electrode surface on which we applied an ac electric field. The MWNTs that had been dispersed into a dielectric solution were directly assembled onto the apex of the AFM tip with the aid of the alignment and attraction of the dielectrophoretic force. To verify the effect of the shape of the tip's apex in the fabrication of a tip attached a single carbon nanotube, we used three types of tips: sharp, blunt and cylindrical. We found from the simulation results and repeated experiments that blunt tips with a 150-250 nm radius are more effective than sharp or cylindrical tips. When we applied an electric field of 0.6-0.7 V_pp/μm, we obtained an AFM tip with a single MWNT attached, and, by using this tip to scan the surface of the reference, we were able to evaluate the performance of the tip. In summary, we have demonstrated that under various experimental conditions the shape of the apex of an AFM's tip deeply affects the fabrication of tips attached a single MWNT.