EFFECT OF FRICTION ON ATOMIC-FORCE MICROSCOPY OF ION-IMPLANTED HIGHLYORIENTED PYROLYTIC-GRAPHITE

An atomic force microscope investigation of the surface of highly orie nted pyrolytic graphite (HOPG) after implantation with 165 keV C+ ions established the presence of a dendritic ridge structure. Examples wer e found for which the image contrast of the ridge structure reversed w hen scanned in the backward direction. This result is demonstrated to be due to variations in the surface friction. The surface of the ridge structure was found to be characterized by a coefficient of friction that was approximately one-half that on the remainder of the surface. Smaller attractive forces between the scanning tip and the surface wer e also observed on the ridges as well. In favorable cases, it is appar ent that consideration of mechanical effects in atomic force microscop y can provide qualitative surface information in addition to the topog raphical images. A comparison is made with unimplanted HOPG, and some instrumental methods for enhancing or reducing the effect of friction are discussed.