Friction forces on hydrogen passivated (110) silicon and silicon dioxide studied by scanning force microscopy

Scanning force microscopy (SFM) was used to study the surface topography and the low load, small contact area frictional behavior of hydrogen passivated (H-terminated) silicon and silicon dioxide in a dry nitrogen atmosphere. The unpassivated samples showed no significant contrast in frictional sliding of a SFM tip between the thermally grown silicon dioxide and the native silicon dioxide that typically covers exposed silicon surfaces. The H-termination of the sample surface leads to an increase in friction by a factor of 2 on silicon, whereas the friction of the silicon dioxide is not influenced. Coefficients of friction were determined by using the two-dimensional histogram technique. On SiO2 and H-terminated Si surfaces, using standard Si3N4 tips, coefficients of friction were determined to be 0.3±0.1 and 0.6±0.1, respectively.