Structural properties of epitaxially grown perfluoro n-alkane thin films prepared by vapor deposition

Structural and orientational studies of epitaxially grown perfluoro n-alkane (CF3(CF2)(18)CF3) thin films evaporated on KCl(001) substrates were conducted by an energy dispersive total reflection X-ray diffractometer, The n-C20F42 molecules grow epitaxially on the KCl(001) surface owing to the slight interaction between the terminal CF3 groups and KCl(001), arranging their [100](hex) directions along the KCl [110] directions, The detailed analysis suggests that most of the molecules crystallize on the epitaxially grown underlayers with the same orientational distribution, although the population of the crystallite with randomly oriented domain structure is slightly increased with increasing thickness. Furthermore, the distorted epitaxial growth with an inclination about +/-5 degrees from the KCI [110] directions was observed and its origin was discussed with respect to the lattice relationship.