Effects of interfacial dielectric layers on the charge transport characteristics in sol-gel based amorphous metal-oxide thin-film transistors

Abstract

We report the effects of interfacial dielectric layers on the field-effect mobility of thin-film transistors (TFTs) with sol-gel based amorphous indium-gallium-zinc oxide (IGZO) films on thermally-grown silicon dioxide (SiO2) and sol-gel based zirconium dioxide (ZrO2) dielectrics. When the field-effect mobility as a function of the channel carrier concentration was extracted, the SiO2 based IGZO-TFT exhibited higher mobility than the ZrO2 based IGZO-TFT at a low carrier concentration. However, the field-effect mobility of the ZrO2 based IGZO-TFT increased as the gate charges increasing due to the gate bias applied. We also investigate the effects of interfacial dielectric layers on the charge transport characteristics in IGZO-TFTs by conducting temperature-dependent field-effect mobility measurements in the temperature range of 120 – 300 K. By analyzing an Arrhenius plot of the results, we confirm that the charge transport of IGZO-TFTs is dominant by the multiple-trapping-and-release model and discuss the effective mobility, which is significantly affected by the interfacial trap level and channel carrier concentration. Finally, we investigate the figure of merit and the activation energy of IGZO-TFTs with ZrO2 dielectrics fabricated by the optimized solution-process developed in this study through comparisons with other sol-gel based amorphous metal-oxide TFTs reported in the literature.