High-performance InGaZnO thin-film transistor incorporating a HfO2/Er2O3/HfO2 stacked gate dielectric

Abstract

In this paper, a HfO₂/Er₂O₃/HfO₂ (HEH) stacked structure was developed as a gate dielectric for amorphous InGaZnO (α-IGZO) thin-film transistor (TFT) applications. Atomic force microscopy and X-ray photoelectron spectroscopy were used to study the morphological and chemical features of Er₂O₃ and HEH films. In comparison to the Er₂O₃ dielectric, the α-IGZO TFT device incorporating a HEH stacked dielectric exhibited a lower threshold voltage of 0.7 V, a higher I_on/I_off current ratio of 2.86 × 10⁷, a larger field-effect mobility of 15.8 cm² V⁻¹ s⁻¹, and a smaller subthreshold swing of 101 mV per dec, suggesting a smooth surface at the dielectric-channel interface. Furthermore, the threshold voltage stability of α-IGZO TFT under positive gate voltage stress can be improved by using a HEH stacked structure.