Scanning tunneling microscope modifications of amorphous Ge–Sb–Te films

Abstract Surface modifications produced in Ge–Sb–Te films by a scanning tunneling microscope have been studied. Three kinds of modifications appear to depend upon the applied voltages to the tip. Positive tip voltages of about 2 V produce depressions accompanying peripheral mounds, which can be accounted for as mechanical scratching by the tip. When the humidity is higher than ∼50%, tip voltages between 5 and 10 V produce depressions with no peripheral mounds, and negative tip voltages of about −10 V produce expansions. These humidity-assisted depression and expansion are assumed to be caused by electrochemical etchings and anodic oxidation processes.