Study of PECVD silicon nitride and silicon oxide gate dielectrics for organic thin-film transistor circuit integration

This paper considers the application of plasma-enhanced chemical vapor deposited (PECVD) silicon nitride (SiNx) and silicon oxide (SiO x) films as gate dielectric for organic thin- film transistors (OTFEs), with solution-processed poly[5,5'-bis(3-dodecyl-2-thienyl)-2,2' - bithiophene)] (PQT-12) as the active semiconductor layer. We examine transistors with SiNX films of varying stoichiometry deposited at 300C as well as 15 0C for plastic compatibility. Transistors show improvement in field-effect mobility (μFE≅ 0.03-0.1 cm²/V-s) and onloff current ratio (ION/IOFF ≤ 10⁸) as the silicon content in SiNX increases. With PECVD SiNx gate dielectric, preliminary devices exhibit a ji of 0.4 cm2/V-s and ION/IOFF of 10 ⁸. The results demonstrate the viability of PECVD SiNx and SiOx gate dielectrics for OTFT circuit integration on rigid and flexible substrates. Copyright © 2007 Materials Research Society.