Gel-based precursors for the high-performance of n-channel GaInSnZnO and p-channel CuGaSnSO thin-film transistors

Abstract

The performance of metal–oxide thin-film transistors (TFTs) should be further improved for the applications of next-generation displays. Here, the developments of gel-derived gallium–indium–tin–zinc oxide (GITZO) for n-channel and copper–gallium–tin–sulfide oxide (CGTSO) for p-channel TFTs are demonstrated. The a-GITZO film by gel-based precursor gives an excellent interface with ZrO_x compared to the GITZO deposited using pristine or purified precursor. The gel-derived GITZO TFT exhibits the saturation mobility (μ_sat) of 28.6 ± 2.15 cm² V⁻¹ s⁻¹, three-fold higher than the pristine one, and excellent bias stability. The boost in GITZO TFT performances is due to the purity of the metal oxide material and higher film density with smooth surface morphology. In addition, the field-effect mobility (μ_FE) of the p-channel copper–tin–sulfide–gallium oxide (CGTSO) TFT could be increased from 1.71 to 4.25 cm² V⁻¹ s⁻¹ using a gel-derived precursor solution. Therefore, these results demonstrate that the gel-derived metal–oxide precursor by the solution process is a promising one for the high performance of the TFT backplane.