High-Performance p-Type SnO Thin-Film Transistors With Superior Bias Stress Stability via Fluorine Plasma Treatment

Tin monoxide (SnO) is a promising p-type oxide semiconductor, but suffers from intrinsic limitations such as low hole mobility ($\mu _{\text {FE}}$), pooron/offcurrent ratio (${I}_{\mathrm {ON}}/{I}_{\mathrm {OFF}}$), large subthreshold swing (SS), and bias instability, which have hindered its practical applications. In this work, fluorine plasma treatment (FPT) is applied to the back channel of SnO thin-film transistors (TFTs). The optimized devices exhibit significantly enhanced performance, including a high$\mu _{\text {FE}}$of 3.0 cm${}^{{2}}\text {/V} \cdot $s, an${I}_{\mathrm {ON}}/{I}_{\mathrm {OFF}}$exceeding$10^{{5}}$, and a low SS of 0.37 V/dec. Bias stress stability is also markedly improved, with the threshold voltage shift ($\Delta {V}_{\text {TH}}$) decreased from 0.74 V (untreated) to 0.34 V (treated) after 10 000 s of stress at$125~^{\circ }$C, corresponding to a 54.1% reduction. These improvements are attributed to fluorine-induced passivation of oxygen vacancies, which suppresses hole trap density without degrading film quality. Finally, an all-oxide inverter based on optimized p-SnO and n-IGZO TFTs is demonstrated, exhibiting an ultrahigh-voltage gain of 470 V/V and a noise margin of 90% at a low supply voltage of 3.0 V. The fabrication process, performed below$250~^{\circ }$C, is compatible with back-end-of-line (BEOL) and flexible substrates, offering a viable route for monolithic 3-D integration.