ZrHfO2-PMMA hybrid dielectric layers for high-performance all solution-processed In2O3-based TFTs

Abstract

Recently inorganic-organic hybrid materials have been quickly arisen as promising dielectric candidates for their applications in the fabrication of solution-processed metal oxide thin-film transistors (TFTs). Based on this, we demonstrate a novel mixed metal oxide hybrid dielectric layer of zirconium hafnium oxide-poly(methylmethacrylate) (ZrHfO2-PMMA) thin films were effectively delivered by simple solution-process by using a low-cost spin coating process at a low temperature of 200 °C. To distinguish the chemical bonding states between inorganic and organic phases FTIR and XPS techniques were performed. The AFM analysis showed the hybrid thin films highly dense with low RMS roughness of around 1-nm. To investigate the dielectric properties of hybrid thin films, MIM capacitor devices were fabricated by using 90-nm thick hybrid dielectric layers exhibiting remarkably low leakage current density of 4.5 × 10−9 A/cm2, capacitance density of 84.5 nF/cm2 with high dielectric constant (k) of 8.4 at 1 kHz. Further, the hybrid dielectric layer was applied as a gate dielectric for fabrication of TFTs with solution processed In2O3 as the channel layer. All solution processed In2O3 TFTs showed an excellent electrical response with electron mobility of 11.2 cm2/V. s, threshold voltage of 1.7 V, Ion/off ratio of 106, and subthreshold swing of 0.58 V/dec. Therefore, our results illustrate the high potential of low-temperature solution processed ZrHfO2-PMMA hybrid thin films for future low-cost TFT applications as gate dielectric candidate.