Molecular-scale non-contact AFM studies of ferroelectric organic thin films epitaxially grown on alkali halides

Epitaxially grown vinylidene fluoride oligomer thin films formed on KCl(0 0 1) surfaces were investigated by ultrahigh vacuum non-contact AFM (UHV-NC-AFM). Molecularly resolved NC-AFM images of organic thin layers on insulating surfaces were successfully obtained for the first time, which revealed the epitaxial growth process on a molecular-scale. It was found that the first monolayer formed on KCl(0 0 1) surface was composed of characteristic honeycomb-like structures while the following upper molecular layers consist of molecular-scale stripe structures. In addition, NC-AFM images of the first monolayer suggest a strong electrostatic interaction between the molecule in the layer and the AFM probe tip.