Deconvolution of tip affected atomic force microscope images and comparison to Rutherford backscattering spectrometry

Abstract

There is distortion in atomic force microscope (AFM) images caused by a nonideal shape and size of the probe tip. This is called tip effect and is due to the convolution of the tip and sample. AFM images of nanometer size islands of zinc deposited on silicon substrates by the ionized cluster beam deposition technique were used to investigate this effect. The number of zinc atoms per unit area determined by each of two methods, the AFM images and Rutherford backscattering spectrometry (RBS) are compared and the AFM reported more zinc than RBS. A partial explanation for this difference is that the convolution of the tip and sample makes the islands appear larger in the AFM data. Previously reported convolution and deconvolution algorithms were implemented to study and simulate the interaction between tip and sample in the AFM. The deconvolution algorithm removes part of the distortion by taking into account the physical volume occupied by the tip which exposes a more accurate image. After deconvolution of the zinc islands images there was better agreement between AFM and RBS results. Deconvolution of other images will also be discussed.