Cones formed during sputtering of InP and their use in defining AFM tip shapes

Small structures, formed on InP surfaces during sputtering, cause loss of depth resolution in sputter-depth profiles but may be conveniently incorporated into a method for studying AFM tip shapes to define resolution in AFM images. The sputtered structures formed here are filaments, often called cones, whose indium tips have a radius of about 10 nm. By sputtering with argon ions in the energy range, 4 keV to 8 keV, it is shown that the height of the filaments is critically dependent on the sample temperature. At room temperature, or below, the height is very small but, at 2608C, they grow to 200 nm. An Arrhenius plot for several temperatures indicates growth, probably by a stress-induced diffusion mechanism driven by charging of the indium cap by the ion beam. AFM images of these structures may be averaged to give reliable pseudo-reconstructions of the AFM tip. Crown Copyright q1999 Published by Elsevier Science B.V. All rights reserved.