Cross-sectional atomic force microscopy imaging of polycrystalline thin films

Atomic force microscopy (AFM) can be used to image cross-sections of thin-f ilm samples. So far, however, it has mainly been used to study cross-sectio ns of epitaxial systems or integrated circuits on crystalline substrates. I n this paper, we show that AFM is a powerful tool to image fractured cross- sections of polycrystalline thin films deposited on crystalline and non-cry stalline substrates, yielding unique information on the three-dimensional p roperties 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 provide s useful additional information. (C) 2000 Elsevier Science B.V. All rights reserved.