DESCRIPTION OF THE FREQUENCY-DEPENDENCE OF THE AMPLITUDE AND PHASE-ANGLE OF A SILICON CANTILEVER TAPPING ON A SILICON SUBSTRATE BY THE HARMONIC APPROXIMATION

The frequency dependence of the amplitude and phase angle of a silicon cantilever tapping on a silicon surface was examined. The amplitude a nd phase angle curves exhibit hysteresis depending on the driving and set-point amplitudes. The main features of these curves are explained in terms of the harmonic approximation. The frequency shifts determine d from the phase curves vary almost linearly as a function of the set- point ratio, in support of the harmonic approximation. The quality fac tor of a tapping cantilever was estimated from amplitude and phase cur ves using the harmonic approximation. The quality factor is reduced by the tip-sample interaction, and this reduction is stronger when the i nteraction is dominated by repulsive forces than by attractive forces. (C) 1998 Elsevier Science B.V. All rights reserved.