Cross talk between friction and height signals in atomic force microscopy

Atomic force and lateral force microscopes use a four quadrant p-i-n detector to measure the motion of a laser beam reflected from the top of a cantilever. If the detector is rotated slightly in the plane of the p-i-n diode, this will cause frictional forces to be detected as a false height signal. In this article, we will show how this coupling between friction and height signals can adversely affect the measurement of topology at height scales below 10 nm. This will be demonstrated with contact mode images of single-walled carbon nanotubes. We will also show how to detect this effect and possible ways to correct for it.