High-mobility intrinsic regime in solution-processed Ti ₃ C ₂ T x MXene TFTs via Li-doped Al ₂ O ₃ and ultra-pure p ⁺ -Si substrate engineering

Ultrathin Ti 3 C 2 T x MXene is a good material for high-performance thin-film transistors (TFTs) because its work function may be changed and it has conductivity that is close to that of metals. However, interfacial charge trapping and dielectric compatibility continue to hides its true potential. This work introduces a method that combines fluoride-free molten-salt-synthesized Ti 3 C 2 T x MXene, which has better material quality and fewer defects during synthesis, with ultraclean interface engineering using atomic-layer-deposited high- κ Li-Al 2 O 3 dielectric and heavily p + -doped silicon substrate. The resulting TFTs exhibit enhanced field-effect mobility (∼25 cm 2 V −1 s −1 ), low subthreshold swing (∼61 Mv dec −1 ), (close to the thermionic limit), minimal hysteresis, and strong stability at low voltage to enhance electrical performance. The platform also improves NH 3 gas sensing, allowing it to be detected at ambient temperature. The study emphasizes interface engineering and dielectric optimization for MXene-based device performance and offers a scalable path for next-generation low-power electronics and sensing.