Abstract
The force curves were measured in the ultra high vacuum (UHV) chamber of an Auger electron spectroscopy (AES) which is generally used for surface analysis. Contacts were made between a gold sphere of about 200μm radius and a silicon wafer. The specimens were sputtered by argon ion to clean their surfaces before the contact. No adsobates were observed in Auger spectra obtained from the sputtered surfaces.
Contact theory for adhesion between an elastic sphere and a rigid plane is described. This theory is based on Johnson, Kendall and Roberts (JKR) theory and Takahashi theory. The total energy in this system is a sum of the elastic energies in the sphere and the stiffness for the measurement system, the change of the surface energy within the contact region and surface-surface interaction outside of the contact region. The force curves are determined by the stiffness and the characteristic distance parameter of Lennard-Jones potential.
Experimental force curves were compared with the theoretical curves. Experimental force curves were influenced by vibration of experimental apparatus. It was suggested that surface-surface interaction was negligible under the order of radius of a gold sphere used to measure. Surface-surface interaction does not become negligible as radius of sphere becomes small. The developed measurement system reveabled informations of interatomic interaction and surface roughness.
