CARBON NANOTUBE PROBE FOR SCANNING TUNNELING MICROSCOPY

Abstract

A simple technique was developed to fabricate carbon nanotube (CNT) probes for scanning tunneling microscope (STM). Multi-walled nanotubes were grown on the apex of the electro-chemically etched tungsten ( W ) tip using thermal chemical vapor deposition (CVD) at normal pressure with H 2 and C 2 H 2 . Nickel ( Ni ) nanoparticles, which were used as the catalyst for CNT synthesis, were applied to the tip apex by dipping the W tip into the Ni nanopowder suspension in ethanol. The diameters of grown nanotubes were in the range of 20 nm to 100 nm. Their lengths were generally less than 1 μm and controlled by growth time. The technique can be readily applied to mass production of CNT STM probes without the use of any sophisticated and expensive equipments. The performance of the fabricated CNT tips was assessed by producing STM images of atomic-resolution.