SCANNING TUNNELING MICROSCOPE INDUCED NANOSTRUCTURING OF A SI(111) AG(ROOT-3X-ROOT-3)R30-DEGREES SURFACE/

An atomically flat Si(111)/Ag(root 3x root 3)R30 degrees surface has b een modified using a scanning tunneling microscope in ultrahigh vacuum . Mesoscopic pits have been created by applying negative voltage pulse s to the sample, while at opposite voltage polarity mounds were formed . Moreover, lines could be written by moving the scanner at elevated v oltages. The threshold voltage for pit formation increases almost line arly with the distance of the tip to the surface and drops to a value below 2 V for the closest approach. At sufficiently high voltages the depth extends beyond the silver layer height. The lateral pit size is well below 8 nm and can be reduced to values between 2 nm and 5 nm for voltages slightly above the threshold. Even selective top layer Ag at om removal has been achieved. (C) 1998 American Institute of Physics.