Low-Temperature-Deposited $\hbox {SiO}_{2}$ Gate Insulator With Hydrophobic Methyl Groups for Bottom-Contact Organic Thin-Film Transistors

This study used a simple deposition method to fabricate hydrophobic SiO₂ as an organic thin-film transistor (OTFT) gate insulator. The SiO₂ gate insulator, which was deposited at 80 °C by plasma chemical vapor deposition using a tetraethoxysilane (TEOS) precursor gas, contained hydrophobic methyl (CH₃) functional groups due to incompletely dissociated TEOS molecules. These CH₃ functional groups made the SiO₂ surface more hydrophobic and, thus, facilitated crystalline growth of the pentacene film, resulting in device performance that could be comparable to OTFTs with SiO₂-based gate insulators deposited at higher temperatures. Therefore, we believe that the proposed 80 °C SiO₂ gate insulator, which delivers a good performance, will enable the potential application of OTFTs on flexible substrates.