Remarkably High Effective Mobility of 301 cm²/V·s in 3 nm Ultra-Thin-Body SnO₂ Transistor by UV Annealing

At an ultra-thin 3 nm SnO₂ channel thickness, a record-high effective mobility (µ_eff) of 301 cm²/V·s, field-effect mobility (µ_FE) of 304 cm²/V·s, and a sharp subthreshold swing (SS) of 201 mV/decade are achieved at a high carrier density (N_e) of 5 × 10¹² cm^-2. These excellent transport properties are attributed to ultraviolet (UV) light annealing. The resulting µ_eff is significantly higher than that of Molybdenum Disulfide (MoS₂) and Tungsten Diselenide (WSe₂), and is more than twice that of single-crystalline Si channel transistors at the same quasi-two-dimensional (2D) thickness of 3 nm (equivalent to five monolayers of MoS₂). UV annealing not only enhances µ_eff and µ_FE but also sharpens the SS, which is crucial for low-power operation. This improved SS is attributed to reduced scattering from charged interface traps, as supported by µ_eff-N_e analysis, thereby increasing the transistor's mobility. The realization of such high-mobility devices at a quasi-2D thickness of only 3 nm is of particular importance for the further downscaling of ultra-thin-body transistors for high-speed computing and monolithic three-dimensional (M3D) integration. Furthermore, the wide bandgap of SnO₂ (3.7 eV) enables operation at relatively high voltages, paving the way for pioneering ternary logic applications.