Field-induced modifications of hydrogenated diamond-like carbon films using a scanning probe microscope

Abstract

Low-conducting hydrogenated diamond-like carbon (a-C:H) films were examined for the purpose of nanometer-scaled modifications under the action of local electrical field. To create the modifications, a series of voltage pulses (either positive or negative, or bipolar) was applied between the sample and the cantilever at regular points along a given line while scanning the probe in contact mode under ambient conditions. It was established that both geometrical and electrical properties of the obtained nano-objects strongly depended on the pulse shape. A nanocavity with a well-conducting bottom was reproducibly formed under the bipolar voltage pulses. Otherwise, the actions mostly resulted in the formation of poorly conducting nanoprotrusions. Evidence was obtained that, in the case of monopolar voltage pulse actions, local heating of the surface layer underneath the probe is a dominant process in the mechanism of the nanoprotrusion formation. We consider that the bipolar pulse actions additionally involve the tip-surface electrostatic interaction which plays an important role in the formation of nanocavities.