Solution-processed amorphous gallium oxide gate dielectric for low-voltage operation oxide thin film transistors

Abstract

Here, gallium oxide (Ga₂O₃) thin films were investigated as gate dielectric for thin-film transistors (TFTs) using the solution process method. The optical, microstructure, morphology, oxygen vacancy defect states and electrical performance metrics of Ga₂O₃ thin films annealed at different stages of temperature were explored. The excellent dielectric property of amorphous Ga₂O₃ thin films was found, but it was deteriorated after crystallization when the annealing temperature increased. The optimized Ga₂O₃ thin film exhibits a low leakage current density of 1.9 × 10^–6 A cm⁻² at 1.5 MV cm⁻² and a large dielectric constant of 10.8. Furthermore, low-voltage operation oxide TFTs were demonstrated using this optimized amorphous Ga₂O₃ as gate dielectric. The device exhibits excellent bias stress stability with a high mobility of 8.5 cm²/Vs, a threshold voltage of -1.4 V, a current on/off ratio of 10⁴ and a subthreshold swing of 0.41 mV/Dec.