Improved gate bias stressing stability of IGZO thin film transistors using high-k compounded ZrO2/HfO2 nanolaminate as gate dielectric

Abstract

The high-k compounded ZrO2/HfO2 nanolaminate gate dielectric is deposited by atomic layer deposition (ALD). And the high-performance InGaZnO (IGZO) thin film transistors (TFTs) are fabricated with the ZrO2/HfO2 nanolaminate gate dielectric. It is found that the ZrO2/HfO2 stacked dielectric presents the smaller root-mean-squared (RMS) and higher breakdown electric field of 6 MV/cm. Furthermore, the TFTs with ZrO2/HfO2 nanolaminate shows excellent properties, such as an increased field-effect mobility of 16.7 cm2/Vs, a deceased subthreshold swing (SS) of 0.64 V/decade, a higher Ion/Ioff current ratio of 108, and a threshold voltage shift (ΔVth) of 0.78 V, 0.32V after gate-bias stress at +5V, -5V for 3600 s, respectively, which are superior compared to TFTs with single ZrO2 dielectric. Thus, the high mobility and high stability TFTs could be regarded as a good candidate for the active matrix organic light emitting diodes (AMOLED) driving.