High-k polymer nanocomposites for gate dielectric applications

Organic electronics such as organic field effect transistors (OFETs) have been recognized as promising technology for next generation electronics, as they are important to realize the fabrication of low cost, light-weight, flexible electronics. Motivated by these recent development, the materials used for these emerging technologies have received increasing attention In addition to the research and development of the organic semiconductors with high charge-mobility, gate dielectrics for organic electronics have been the focus of recent attention as well. For this application, the dielectric materials should ideally exhibit good compatibility with flexible substrate, solution processibility, and larger capacitance to increase the drain current while operating at low biases. Complementary to conventional high dielectric constant (k) inorganic materials and those readily accessible and solution processible polymer materials, polymer/inorganic hybrid films which could be deposited by spin-coating are well suited to provide a better solution. In this study, a solution processible high-k barium titanate (BT)/benzocyclobutene (BCB) nanocomposite was developed. Dielectric and electrical properties of the as prepared BT/BCB nanocomposites were investigated. A k value of 50 and a capacitance density of 19 nF/cm
²
were achieved for a nanocomposite with 50 vol. % BT loading at 10 kHz. And the dielectric breakdown strength was as high as 1.65 MV/cm, which is even higher than those of some polymers themselves. The preliminary result of the electrical output of OFET prototype incorporating high-k BT/BCB nanocomposite as gate insulator layer shows that the OFET can be operated at very low voltage. This demonstrates the feasibility of using high-k BT/BCB nanocomposite as gate dielectric insulator in the OFET.