A Microstructural Investigation of PMMA/SAM TiO2 dielectric thin films for OFETs

Abstract

Poly (methyl methacrylate) (PMMA) and TiO₂ have been used as dielectric materials of organic field effect transistors (OFETs) for improved dielectric constants and better interfaces between the dielectric layers and organic semiconductor films. In this study, PMMA/TiO₂ layers were fabricated using self-assembly monolayer (SAM) TiO₂ films sandwiched between the PMMA layers. Dielectric constants of the PMMA/TiO₂ layers were studied from capacitance-frequency characteristics of metal/insulator/metal structures. The dielectric constant was found to increase with increased TiO₂ thickness, i. e. increased number of soaking cycles during SAM process. The dielectric constant at a frequency of 1k was 15.7, which was approximately 4 times higher than that of the bare PMMA. However, after an optimum number of soaking cycles was reached, the dielectric constant decreased due to current leakage.