A Study on Solution-Processed Y2O3 Films Modified by Atomic Layer Deposition Al2O3 as Dielectrics in ZnO Thin Film Transistor

In this work, Y2O3–Al2O3 dielectrics were prepared and used in ZnO thin film transistor as gate insulators. The Y2O3 film prepared by the sol–gel method has many surface defects, resulting in a high density of interface states with the active layer in TFT, which then leads to poor stability of the devices. We modified it by atomic layer deposition (ALD) technology that deposited a thin Al2O3 film on the surface of a Y2O3 dielectric layer, and finally fabricated a TFT device with ZnO as the active layer by ALD. The electrical performance and bias stability of the ZnO TFT with a Y2O3–Al2O3 laminated dielectric layer were greatly improved, the subthreshold swing was reduced from 147 to 88 mV/decade, the on/off-state current ratio was increased from 4.24 × 106 to 4.16 × 108, and the threshold voltage shift was reduced from 1.4 to 0.7 V after a 5-V gate was is applied for 800 s.