Morphology and electrical transport in pentacene films on silylated oxide surfaces

A study comparing the morphology and electrical transport properties of pentacene films on underlayers of different self-assembled monolayers (SAMs) is presented. The SAMs studied as underlayers were phenyltrichlorosilane, n-octadecyltrichlorosilane, and t-butyldiphenylchlorosilane. Pentacene thin films were grown by vacuum sublimation on SiO2 surfaces treated with self-assembled monolayers. During deposition, substrates were held at a temperature of 70 degreesC. The morphologies of the films at different stages of deposition were studied by atomic force microscopy, and the transport properties of the films were characterized by I-V measurements in a simple field-effect transistor (FET) structure. The SAM underlayers strongly influence the film morphology in the first few molecular layers and hence significantly impact the electrical transport in the resulting FETs.