Rubrene thin-film transistors with crystalline channels achieved on optimally modified dielectric surface

We report on the fabrication of rubrene thin-film transistors (TFTs) with surface-modified dielectrics adopting several kinds of self-assembled-monolayer (SAM) on SiO2/p+−Si substrate. With the dielectric of lower surface energy, the crystalline rubrene growth or amorphous-to-crystalline transformation kinetics is faster during in-situ vacuum post-annealing, which was performed after rubrene vacuum deposition. In the present study, hexamethyldisilazane (HMDS) was finally determined to be the most effective SAM interlayer for polycrystalline rubrene channel formation. Our rubrene TFT with HMDS-coated SiO2 dielectric showed quite a high field mobility of ∼10−2 cm2/V s and a high on/off current ratio of ∼105 under 40 V.