High-performance InO_x/GaO_x bilayer channel thin-film transistors made using persistent high-surface-energy induced by photochemical activation

In this paper, we report high-mobility InO_x/GaO_x bilayer channel thin-film transistors (TFTs) fabricated using the persistent high-surface-energy characteristic of photochemically activated metal-oxide films. The photochemically-activated metal-oxide films exhibited persistent high surface-energy characteristics compared to a thermally annealed film, which enabled the facile vertical stacking of oxide films using a solution-based process. By using the photochemical activation process as an annealing method and by employing an InO_x/GaO_x bilayer channel structure, high-mobility oxide TFTs with saturation field-effect mobilities as high as 15.7 cm²/V-s were obtained with an average value of 11.2 ± 1.9 cm²/V-s. Various spectroscopic and surface analyses were performed to elucidate the persistent high surface-energy behavior and the dynamic changes in surface states.