High Mobility IZTO Thin-Film Transistors Based on Spinel Phase Formation at Low Temperature through a Catalytic Chemical Reaction

In this paper, In_0.22 Zn_δ Sn_{0.78- δ} O_{1.89- δ} (δ = 0.55) films with a single spinel phase are successfully grown at the low temperature of 300 °C through careful cation composition design and a catalytic chemical reaction. Thin-film transistors (TFTs) with amorphous In_{0 .22} Zn_δ Sn_{0.78- δ} O_{1.89- δ} (δ = 0.55) channel layers have a reasonable mobility of 41.0 cm² V^-1 s^-1 due to the synergic intercalation of In and Sn ions. In contrast, TFTs with polycrystalline spinel In_{0 .22} Zn_δ Sn_{0.78- δ} O_{1.89- δ} (δ = 0.55) channel layers, achieved through a metal-induced crystallization at 300 °C, exhibit a remarkably high field-effect mobility of ≈83.2 cm² V^-1 s^-1 and excellent stability against external gate bias stress, which is attributed to the uniform formation of the highly ordered spinel phase. The relationships between cation composition, microstructure, and performance for the In₂ O₃ -ZnO-SnO₂ ternary component system are investigated rigorously to attain in-depth understanding of the roles of various crystalline phases, including spinel Zn_{2- y} Sn_{1- y} In_{2 y} O₄ (y = 0.45), bixbyite In_{2-2 x} Zn_x In_x O₄ (x = 0.4), rutile SnO₂ , and a homologous compound of compound (ZnO)_k (In₂ O₃ ) (k = 5). This work concludes that the cubic spinel phase of Zn_{2- y} Sn_{1- y} In_{2 y} O₄ (y = 0.45) film is a strong contender as a substitute for semiconducting polysilicon as a backplane channel ingredient for mobile active-matrix organic light-emitting diode displays.