Ladder-type silsesquioxane copolymer gate dielectrics for gating solution-processed IGZO field-effect transistors

Field-effect transistors (FETs) based on solution-processed indium-gallium-zinc oxide (IGZO) exhibited excellent electrical properties, including a high carrier mobility over 1 cm(2)/V s and an on/off current ratio over 10(7). Solution-processable gate dielectric materials with excellent electrical strength were required instead of inorganic oxide gate dielectrics such as SiO2, Al2O3, and HfO2. In this manuscript, we demonstrated the use of a ladder-type poly(phenyl-co-methacryl silsesquioxane) (PPMSQ) copolymer as a gate dielectric in IGZO FETs. Methacryloxypropyl groups in the copolymer were introduced to crosslink the polymer chains via thermal annealing. Thermal annealing at 200 degrees C enhanced the electrical strength of the gate dielectric layer because of the formation of a network structure with a reduced free volume. The resulting IGZO FETs based on 200 degrees C-annealed ladder-type PPMSQ gate dielectrics exhibited an electron mobility of 1.2 (+/- 0.05) cm(2)/V s, a threshold voltage of 17 (+/- 2) V, and an on/off current ratio of 1.5 (+/- 0.7) x 10(8). The use of the polymeric ladder-type PPMSQ gate dielectrics for gating the IGZO FETs provided a novel approach to realizing future flexible electronics. (C) 2017 Elsevier B.V. All rights reserved.