Effect of Electrical Performance and Reliability by Adjustment of the Sequence and Concentration of HfAlO_x on IWO Thin-Film Transistors

We investigated the electrical and material characteristics of atomic layer deposition (ALD) deposition with different sequences and concentrations of HfAlOx in Indium-Tungsten-Oxide thin film transistors (IWO-TFTs). Under the 1A10H case, we observed the best electrical properties, with threshold voltage (Vt) closest to 0 V, Ion/Ioff value of approximately 6.7×10 ⁷ , subthreshold swing (SS) of 95 mV/dec, smaller interface trap density (Nit) of 5.7×10 ¹² cm ^-2 , and superior immunity to stress-induced degradation. The X-ray photoelectron spectroscopy (XPS) results provided insights into the stability of the interface between the gate dielectric layer and the channel layer. Specifically, the 1A10H conditions exhibited a more stable interface with fewer defects. Furthermore, the choice of HfO ₂ as the interface layer material between HfAlO _x and IWO, compared to Al ₂ O ₃ , demonstrated superior performance for different Hf/Al sequence combinations. These findings offer promising directions for enhancing the stability of IWO-TFTs through improvements in the interface between the channel layer and the gate dielectric layer.