Aqueous-solution-synthesized gallium oxide dielectrics for high-mobility thin-film transistors enhanced by phosphorus incorporation

Gallium oxide (Ga2O3) is widely used as an ultra-wide bandgap semiconductor in emerging optoelectronics. Recent works show that Ga2O3 could be a promising high-κ dielectric material due to its high thermal stability, excellent moisture resistance, and ease of processing from solution phase. However, the dielectric properties of pristine Ga2O3 could be further improved. Here, aqueous-solution-synthesized Ga2O3 with excellent dielectric properties are achieved by phosphorus (P) incorporation. Using an Ga2O3 dielectric with optimal P (20 at. %) incorporation, oxide thin-film transistors (TFTs) exhibit enhanced performance with a mobility of 20.49 ± 0.32 cm2 V−1 s−1, subthreshold swing of 0.15 ± 0.01 V/dec, current on/off ratio >106, and superior bias stress stability. Systematic analyses show that proper P incorporation considerably reduces oxygen-related defects (oxygen vacancies and hydroxyls) in Ga2O3, resulting in better dielectric and TFT performance.