Scanning Probe Microscopy

Abstract

This article describes new perspectives on SPM-related science and technology, based on systems and control theory. These perspectives have led to a better understanding of SPM technology, overcome hurdles that limited the efficacy of SPM, and resulted in new modes of SPM-based interrogation. ThNcAFM, based on systems principles, has made it possible to image with resolution as high as 0.25 Aring in ambient conditions. The orders-of-magnitude improvements achieved in areas such as precision positioning, sample imaging, and sample detection rates emphasize the potential of systems tools in nanotechnology. The concept of using models in online operation has significant potential for SPM. For instance, TF-AFM, which uses models for online operation, resolves competing objectives of high resolution and detection rate by using a design from a systems perspective that makes detection bandwidth independent of the quality factor of the probe and, therefore, independent of resolution. The systems perspective also facilitates the interpretation of data since it provides a precise means for delineating the effects of the inherent dynamics of the interrogation system from the properties of the sample being probed. Devices such as SPMs are sensitive to operating conditions, ambient conditions, and modeling inaccuracies. Modern control theory provides a framework where such challenges can be effectively addressed. This aspect translates to reliable experiments in terms of repeatability, which is crucial in many nanoscience studies.