Application of atom probe tomography to the investigation of atomic force microscope tips and interfacial phenomena

Abstract

This dissertation demonstrates the research effort to extend the analytical capabilities of atomic force microscopy (AFM) by utilizing atom probe tomography (APT) to investigate AFM tips for the first time. Novel techniques were developed to enable successful analysis of various AFM tips and layers created on the tips. Initial investigations focused on comparing results obtained from as received Si AFM tips to a standard Si APT sample. It was found that by using careful alignment and stiffer cantilevers (>25N/m) AFM tips are readily analyzable by APT. The techniques were then applied to commercially available coated Si AFM tips and high aspect ratio metallic needle tips to demonstrate the broad applicability. A new method to calibrate the optical sensitivity of AFM cantilevers was developed to eliminate damage to the AFM tip. Finally the new calibration method was utilized in the investigation of transferred material from AFM sliding experiments. It was found that the transferred material was readily detected and characterized. The successful results demonstrate the ability of APT application to AFM tips enhancing the information from AFM experiments and opening new areas of investigation.