Effects of Post-UV/Ozone Treatment on Electrical Characteristics of Solution-Processed Copper Oxide Thin-Film Transistors

To realize oxide semiconductor-based complementary circuits and better transparent display applications, the electrical properties of p-type oxide semiconductors and the performance improvement of p-type oxide thin-film transistors (TFTs) are required. In this study, we report the effects of post-UV/ozone (O-3) treatment on the structural and electrical characteristics of copper oxide (CuO) semiconductor films and the TFT performance. The CuO semiconductor films were fabricated using copper (II) acetate hydrate as a precursor material to solution processing and the UV/O-3 treatment was performed as a post-treatment after the CuO film was fabricated. During the post-UV/O-3 treatment for up to 13 min, the solution-processed CuO films exhibited no meaningful change in the surface morphology. On the other hand, analysis of the Raman and X-ray photoemission spectra of solution-processed CuO films revealed that the post-UV/O-3 treatment induced compressive stress in the film and increased the composition concentration of Cu-O lattice bonding. In the post-UV/O-3-treated CuO semiconductor layer, the Hall mobility increased significantly to approximately 280 cm(2) V-1 s(-1), and the conductivity increased to approximately 4.57 x 10(-2) ohm(-1) cm(-1). Post-UV/O-3-treated CuO TFTs also showed improved electrical properties compared to those of untreated CuO TFTs. The field-effect mobility of the post-UV/O-3-treated CuO TFT increased to approximately 6.61 x 10(-3) cm(-2) V-1 s(-1), and the on-off current ratio increased to approximately 3.51 x 10(3). These improvements in the electrical characteristics of CuO films and CuO TFTs can be understood through the suppression of weak bonding and structural defects between Cu and O bonds after post-UV/O-3 treatment. The result demonstrates that the post-UV/O-3 treatment can be a viable method to improve the performance of p-type oxide TFTs.