Characterization of MIS structures and PTFTs using TiOx deposited by spin-coating

This paper presents a method to deposit titanium oxide (TiOx) films from a sol containing IV titanium isopropoxide Ti[OCH(CH3)2]4, 2-methoxyethanol, CH3OCH2CH2OH and ethanolamine H2NCH2CH2OH, in order to obtain layers with thickness above 220 nm with the required characteristics to be used in Metal-Insulator-Semiconductor, MIS, structures and polymeric thin film transistors, PTFTs. The effect of using different component ratios is described. The dielectric constant was in the order of 12, the critical electric field was 5 × 105 V/cm and the density of states at the interface was less than 1 × 1011 cm−2. The analysis of MIS structures prepared with these TiOx layers shows that they are suitable for using in PTFTs. The fabrication of independent bottom gate PTFTs with poly(3-hexylthiophene), P3HT, on top of the TiOx layer is described, obtaining a major reduction in the operation voltage range from −30 V to −4 V, while maintaining the typical mobility for P3HT PTFTs.