In this paper, three different tips are employed, i.e., the carbon nanotube tip, monocrystalline silicon tip and silicon nitride tip. Resorting to atomic force microscope （AFM）, they are used for measuring the surface roughness of indium tin oxide （ITO） film and the immunoglobulin G （IgG） proteins within the scanning area of 10 μm×10 μm and 0.5 μm×0.5 μm, respectively. Subsequently, the scanned surface of the ITO film and IgG proteins are analyzed by using fractal dimension. The results show that the ffactal dimension measured by carbon nanotube tip is biggest with the highest frequency components and the most microscopic information. Therefore, the carbon nanotube tip is the ideal measuring tool for measuring super-smooth surface, which will play a more and more important role in the high-resolution imaging field.
WANG Jinghe WANG Hongxiang XU Zongwei DONG Shen WANG Shiqian ZHANG Huali
