High-resolution atomic force microscope nanotip grown by self-field emission

A technique to grow a single tungsten filament tip on a tapping mode atomic force microscope (AFM) tip by a process of self-field emission in the presence of tungsten carbonyl is demonstrated. Such filaments have a tip radius of 1-2 nm and are grown to lengths ranging from 400 nm to 3 mum and a shank diameter of about 60-90 nm. Images of germanium nanocrystals and porous alumina membranes show much higher resolution and definition than standard AFM tips. The tip shows no degradation even after 10 h of scanning, demonstrating its utility as a practical tip. The self-aligned nature of the growth makes it a very simple nanotip fabrication technique. (C) 2002 American Institute of Physics.