High Performance of InGaZnO TFTs Using HfxAlyOz Nanolaminates as Gate Insulators Prepared by ALD

Abstract

In this study, HfxAlyOz nanolaminate, single-layer Al2O3, and HfO2 gate insulators were fabricated by atomic layer deposition (ALD) to successfully integrate the InGaZnO (IGZO) thin-film transistors (TFTs). Compared with single-layer HfO2-based TFTs, the HfxAlyOz-based IGZO TFTs showed a larger field-effect mobility of 10.31 cm2/Vs and a smaller subthreshold swing of 0.12 V/decade. Moreover, it showed a smaller threshold voltage shift of 0.5 V than that of HfO2-based TFTs under gate-bias stress at +5 V for 900 s due to the smooth surface. Moreover, the high dielectric HfxAlyOz nanolaminate had a larger equivalent SiO2 thinness than that of Al2O3 gate insulators, which are beneficial in applications of high-resolution display. Thus, the high mobility and high stability TFTs could be regarded as good candidates for active-matrix flat panel displays.