Effects of gate insulators on the performance of a-IGZO TFT fabricated at room-temperature

Abstract

Effects of gate insulators for oxide TFTs have been investigated by two types of a-IGZO TFTs with high-k and low-k oxides. TFTs with low-k oxides have low on-current due to the low-capacitances of the materials. HfO2 has been used as high-k gate insulator, because HfO2 is one of most promising high-k oxides with the high capacitance due to its high dielectric constant. We have fabricated a-IGZO TFTs with SiO2 and HfO2. And their performances are compared, such as mobility, threshold voltage, subthreshold swing, on-to-off current ratio, hysteresis, and bias-sensitivity. TFT with HfO2 gate insulator shows better performances than those of TFT with SiO2 gate insulator. (C) 2011 Elsevier B.V. All rights reserved.