Comparative Study on Performance of IGZO Transistors With Sputtered and Atomic Layer Deposited Channel Layer

The structural, chemical, and electrical properties of amorphous indium gallium zinc oxide (a-IGZO) films by magnetron sputtering and atomic layer deposition (ALD) were investigated where both a-IGZO films had a comparable cation composition. The ALD-derived a-IGZO film exhibited the higher atomic packing density, the effective suppression of trap-like oxygen vacancy defect (V_O), and the enhancement in the hybridization of the sp orbital of In, Ga, and Zn cations compared to those of the sputtered a-IGZO film. Hence, a significant improvement in terms of the field-effect mobility was observed for the thin-film transistors with an In_0.50Ga_0.34Zn_0.16O channel by ALD (36.6 cm $^{\textsf {2}}/\text{V}\cdot \text{s}$ ) compared to that of the sputtered In_0.48Ga_0.38Zn_0.14O transistor (20.1 cm $^{\textsf {2}}/\text{V}\cdot \text{s}$ ); the ${I}_{\text {ON/OFF}}$ ratios for both were ~10⁷. Simultaneously, the gate bias stress stability and photobias stress stability were also improved for the IGZO transistors with an ALD-derived channel, which can be explained by its reduced trap-like V_O density.