The effects of gallium on solution-derived indium oxide-based thin film transistors manufactured on display glass

Metal oxide semiconductor TFTs have been considerably investigated as a promising alternative to hydrogenated amorphous silicon and organic semiconductors. While many multicomponent oxide TFTs have been studied, there are only a few reports of TFTs using amorphous indium gallium oxide channel layers. In this study, the effects of gallium atomic ratio on the performance of solution-derived indium oxide-based TFTs on display glass were investigated for the first time. The morphological, optical, and electrical properties of IGO channel layers with different gallium atomic ratios were characterized. IGO TFTs with various chemical compositions were compared and interpreted based on the analysis of In3d, Ga2p, and O1s XPS data. It was found that gallium dopant suppresses the generation of oxygen vacancies, while promoting the formation of oxygen in the oxide lattice without oxygen vacancies by reducing the density of hydroxides. By adjusting the atomic ratio of gallium, we were able to fabricate IGO TFTs on display glass with an average field-effect mobility as high as 6.1 cm2 V−1 s−1, Von = −2 V, and on–off ratio of 107.