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

We investigated the electrical and material characteristics of atomic layer deposition (ALD) deposition with different sequences and concentrations of HfAlO
_x
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 × 107, subthreshold swing (SS) of 95 mV/dec, smaller interface trap density (Nit) of 5.7 × 1012 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.