EFFECTS OF TIP SIZE AND ASYMMETRY ON SCANNING TUNNELING MICROSCOPE TOPOGRAPHS

We investigated broadening and skewing of scanning tunneling microscope topographs caused by tip size and symmetry. Model images were generated numerically by convoluting a gaussian response function for the tip with an idealized graphite image. Atomic-scale features were retained even for a 9.4 Å FWHM tip function, which demonstrated that single-atom tips are not required to obtain atomic resolution topographs. Model tips with an elliptical radial cross section produced many of the familiar skewed images of graphite. Such response functions could also be used to remove the skew from an experimental topograph, and thus provide an approximation for the shape of the physical tip. © 1990.