p‑Type Oxide Thin-Film Transistor with Unprecedented Hole Field-Effect Mobility for an All-Oxide CMOS CFET-like Inverter Suitable for Monolithic 3D Integration

The lack of low temperature processable, high-performance p-type oxide thin-film transistors (TFTs) limits their implementation in monolithically integrated back-end-of-line (BEOL) CMOS circuitries. In this work, we demonstrate a reactive magnetron-sputtered SnO_x TFT with unprecedented hole field-effect mobility (μ_FE‑hole) of 38.7 cm²/V·s, as well as an on/off current ratio (I_on/off) of 2.5 × 10³ and lower subthreshold swing (SS) of 240.9 mV/dec when compared to reported works on p-type oxide-based TFTs. Material characterization correlated with the SnO_x TFTs’ electrical behavior elucidated the performance to the structural and compositional phase modulation of the SnO_x thin films, modulated by O₂ partial pressure during deposition and post-encapsulation annealing. By integrating the SnO_x TFT with an IGZO TFT in both planar and stacked complementary FET-like form, we demonstrated a true oxide-based CMOS inverter, achieving one of the highest voltage gains of 57 and the lowest static power consumption down to 34 pW for both on and off states.