Cross-Sectional Atomic Force Microscopy Imaging of Polycrystalline Thin Films

Atomic force microscopy (AFM) can be used to image cross-sections of thin-film samples. So far, however, it has mainly been used to study cross- sections of epitaxial systems or integrated circuits on crystalline substrates. In this paper, we show that AFM is a powerful tool to image fractured cross-sections of polycrystalline thin films deposited on crystalline and non-crystalline substrates, yielding unique information on the three-dimensional properties of the cross-sections, with a spatial resolution in the nm range. Original images of three different heterostructure systems are presented: Si(wafer)/SnO₂/CdS/CdTe, glass/Mo/Cu(In,Ga)Se₂/CdS/ZnO, and glass/SnO₂/WO₃. We discuss the results by comparing AFM and scanning electron microscopy (SEM) images, and explain, for the different materials, why the AFM provides useful additional information. (C) 2000 Elsevier Science B.V.