Threshold behavior of nanometer scale fabrication process using scanning tunneling microscopy

The fabrication process on a graphite surface is investigated using scanning tunneling microscopy, with emphasis on the effects of high electric field associated with voltage pulse. We have demonstrated that two distinct types of features can be repeatedly produced and are found to be correlated with tip-sample separation, displaying a threshold behavior. By correlating the observation with the general trend of tunneling barrier height versus tip-sample separation, it is suggested that field emission and electrical breakdown are the driving mechanisms for generating craters and mounds, respectively. (C) 1997 American Institute of Physics.