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 cm 2 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 In 2 O 3 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 In 2 O 3 crystalline phase and large grain size of the IGO film.