In this study, the poly(2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane-co-cyclohexyl methacrylate) [p(V4D4-co-CHMA)] copolymer was developed for use as a gate dielectric in molybdenum disulfide (MoS2) field-effect transistors (FETs). The p(V4D4-co-CHMA) copolymer was synthesized via the initiated chemical vapor deposition (iCVD) of two types of monomers: 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (V4D4) and cyclohexyl methacrylate (CHMA). Four vinyl groups of V4D4 monomers and cyclohexyl groups of CHMA monomers were introduced to enhance the electrical strength of gate dielectrics through the formation of a highly crosslinked network and to reduce the charge trap densities at the MoS2-dielectric interface, respectively. The iCVD-grown p(V4D4-co-CHMA) copolymer films yielded a dielectric constant of 2.3 and a leakage current of 3.8 × 10-11 A/cm2 at 1 MV/cm. The resulting MoS2 FETs with p(V4D4-co-CHMA) gate dielectrics exhibited excellent electrical properties, including an electron mobility of 35.1 cm2/V s, a subthreshold swing of 0.2 V/dec, and an on-off current ratio of 2.6 × 106. In addition, the environmental and operational stabilities of MoS2 FETs with p(V4D4-co-CHMA) top-gate dielectrics were superior to those of devices with SiO2 back-gate dielectrics. The use of iCVD-grown copolymer gate dielectrics as demonstrated in this study provides a novel approach to realizing next-generation two-dimensional electronics.
Bibliographical noteFunding Information:
This research was supported by the Basic Science Research Program through a National Research Foundation of Korea grant funded by the Korean Government (MEST) (2017R1A2B2005790, 2017R1A4A1015400, and 2010-0027955).
© 2018 American Chemical Society.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films