The growth of organic thin films on silicon substrates studied by X-ray reflectometry

Abstract

The growth of organic thin films of 3,4,9,10-perylene-tetracarboxylic-dianhydride on silicon substrates has been studied by X-ray reflection and X-ray diffraction methods to examine the crystallinity and homogeneity of the films. It was found that at substrate temperatures below 50°C the films have an extremely flat surface (roughness less than 10 Å). The molecules are oriented preferentially parallel to the substrate surface. The size of the crystallites increases with increasing substrate temperature. At a substrate temperature between 50 °C and 100 °C we find a rather abrupt transition from a smooth film to island growth, while the molecules retain their preferred orientation.