FIELD EVAPORATION BETWEEN A GOLD TIP AND A GOLD SURFACE IN THE SCANNING TUNNELING MICROSCOPE CONFIGURATION

Mounds of gold atoms of horizontal size less than 200 angstrom and height < 20 angstrom, and pits of width < 50 angstrom and depth < 10 angstrom can be produced on a gold surface with nearly equal probabilities by applying voltage pulses to a gold tip in the scanning tunneling microscope. We study the effects of the polarity and the height of the applied voltage pulses, and those of the atmospheric environments. Our data show that field evaporation can occur both in positive and negative fields, but in ultrahigh vacuum, a tip can sustain itself only if it is in negative polarity.