Efficient Oxygen-Vacancy Suppression and Electrical Stabilization of Solution-Processed In₂O₃:Q (Q = S, Se) Thin-Film Transistor with Chalcogen Alloying

Transparent oxide semiconductors are successfully implemented as thin-film transistors (TFTs) for large-area display applications with superior electrical performance in comparison with that of conventional amorphous silicon. However, further development of high-performance oxide semiconductors is hindered by the trade-off between mobility and stability. Mixed metal composition containing heavy metal cations shows high-mobility/low-stability and light metal cations exhibits low-mobility/high-stability. A novel material design strategy for realizing a high-performance oxide semiconductor for TFTs through partial substitution of Se or S for O in In₂O₃ is reported. In contrast to the conventional small-sized Ga substitution for suppressing oxygen vacancies, the replacement of O by Se or S results in lattice stabilization and oxygen-vacancy suppression, consequently stabilizing Se- or S-incorporated In₂O₃ TFTs. In₂O₃:Se TFTs exhibit an average field-effect mobility of 6.1 cm² V⁻¹s⁻¹, ON/OFF current ratio (I_on/I_off) of 10⁸, and excellent operational stability with threshold voltage shift values of <0.10 V at a positive and negative bias stress for 10 000 s. Furthermore, the seven-stage ring oscillator circuit operating at a supply bias of 20 V exhibits an oscillation frequency of >805 kHz and a corresponding propagation delay of <90 ns per stage.