A Comparative Study Of Plasma-enhanced Chemical Vapor Gate Dielectrics For Solution-processed Polymer Thin-film Transistor Circuit Integration

摘要

This paper considers plasma-enhanced chemical vapor deposited (PECVD) silicon nitride (SiN_x) and silicon oxide (SiO_x) as gate dielectrics for organic thin-film transistors (OTFTs), 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 SiN_x films of varying composition deposited at 300 ℃ as well as 150 ℃ for plastic compatibility. The transistors show over 100% (two times) improvement in field-effect mobility as the silicon content in SiN_x increases, with mobility (μ_(FE)) uP to 0.14 cm~2/V s and on/off current ratio (I_(ON)/I_(OFF)) of 10~8. With PECVD SiO_x gate dielectric, preliminary devices exhibit a μ_(FE) of 0.4 cm~2/V s and (I_(ON)/I_(OFF)) of 10~8. PQT-12 OTFTs with PECVD SiN_x and SiO_x gate dielectrics on flexible plastic substrates are also presented. These results demonstrate the viability of using PECVD SiN_x and SiO_x as gate dielectrics for OTFT circuit integration, where the low temperature and large area deposition capabilities of PECVD films are highly amenable to integration of OTFT circuits targeted for flexible and lightweight applications.