Scanning tunneling microscopy of plasma-solid surface interface

A plasma-solid surface reaction on the nanometer scale was observed in situ for the first time. This was achieved by employing special scanning tunnel ing microscopy (STM) that could be operated in a plasma environment. To pre vent current due to noise from the plasma, the probe tip was coated with ep oxy grease and insulating glass. The apex of the probe tip was sharpened by a focused ion beam (FIB). This special STM had sufficient stability and re producibility to measure a 10 x 10 mum(2) region for more than 5 h in a pla sma environment. Using this apparatus, sequential in situ STM images of hig hly oriented pyrolytic graphite (HOPG) were obtained in a radio-frequency ( rf) (430 MHz) low-pressure (1 torr) air glow plasma. These images revealed that a projection of over 100 nm in height was etched by the plasma and rem oved. (C) 2000 Elsevier Science S.A. All rights reserved.