Nucleation of pentacene thin films on silicon dioxide modified with hexamethyldisilazane

Nucleation and growth of pentacene on silicon dioxide surfaces modified with hexamethyldisilazane, HN[Si(CH3)3]2, has been examined using supersonic molecular beam techniques and atomic force microscopy. Similar to growth on clean SiO2 surfaces, the rate of deposition at a fixed incident flux decreases with increasing kinetic energy of incident pentacene, indicative of trapping mediated adsorption. Unlike clean, unmodified SiO2 surfaces, however, growth on the modified surface exhibits characteristics of heterogeneous nucleation, where the maximum island density is independent of deposition rate. Further, islands in the submonolayer regime are two molecules high, unlike the one molecule high islands observed on clean SiO2.