High-Mobility Thin-Film Transistors with Polycrystalline In–Ga–O Channel Fabricated by DC Magnetron Sputtering

Oxide thin-film transistors (TFTs) were fabricated using a polycrystalline In–Ga–O (IGO) thin film as the n-channel active layer by direct current magnetron sputtering. The 50-nm-thick IGO TFT showed a field-effect mobility of 39.1 cm2 V-1 s-1, a threshold voltage of 1.4 V, and a subthreshold gate voltage swing of 0.12 V/decade. The polycrystalline IGO thin film showed the cubic bixbyite structure of In2O3 without an obvious preferred orientation. The average grain size of polycrystalline IGO was approximately 10 µm. The high mobility of IGO TFT is related to the In2O3 crystalline phase and large grain size of the IGO film.