Homoepitaxial growth of α-hexathiophene

The homoepitaxial growth by organic molecular beam epitaxy of the organic semiconductor α-hexathiophene has been described by scaling theories and classical kinetic tools. Atomic force microscopy has been employed for experimentally extracting kinetic parameters of the growth, in a range of substrate temperatures between 298 and 393 K. Within this range, the critical nucleus size of two-dimensional homoepitaxial islands has been observed to change from one to three molecules, and nucleation has been found to be an activated process with an energy barrier of 0.73 ± 0.18 eV (17 ± 4 kcal/mol). This energy barrier is consistent with a growth mechanism in which substantial material re-evaporation occurs.