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)Se-2/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. All rights reserved.