Characterization of Polymethyl Methacrylate (PMMA) Layers for OTFTs Gate Dielectric

Polymethyl methacrylate (PMMA) is an organic material widely used in electronic photoresists. Recently, pentacene OTFTs were fabricated using this material as dielectric film, which is considered to have a dielectric constant similar to SiO₂. In this paper we characterize PMMA layers in order to determine its dielectric constant, current density and interface states density when used as a gate dielectric in the manufacturing of organic thin film transistors. MIS capacitors were prepared, with PMMA as a dielectric, chromium as gate metal and aluminum as the back contact on Si wafers. I-V and C-V characteristics measurements reported a dielectric constant of 2.6 at 1 MHz. Current density across the dielectric is less than 2times10 ^-8A/cm² and interface states density is below 2times10¹²cm^-2