High-Performance Tin Oxide Thin-Film Transistors Realized by Codoping and Their Application in Logic Circuits

Tin oxide is a promising channel material, offering the advantages of being low-cost and environmentally friendly and having a wide band gap. However, despite the high electron mobility of SnO₂ in bulk, the corresponding thin-film transistors (TFTs) generally exhibit moderate performance, hindering their widespread application. Herein, we proposed a codoping strategy to improve both the electrical property and the stability of SnO₂ TFTs. A comparative analysis between doped and undoped SnO₂ was conducted. It is observed that taking advantage of the difference in ionic radii between two dopants (indium and gallium) and the tin ions in the host lattice can effectively reduce impurity-induced strain. Additionally, we investigated the effect of codoping content on SnO₂ TFTs. The optimal codoped SnO₂ (TIGO) TFTs demonstrate high performance, featuring a field-effect mobility of 15.9 cm²/V·s, a threshold voltage of 0.2 V, a subthreshold swing of 0.5 V/decade, and an on-to-off current ratio of 2.2 × 10⁷. Furthermore, the devices show high stability under both positive and negative bias stress conditions with a small threshold voltage shift of 1.8 and -1.2 V, respectively. Utilizing the TIGO TFTs, we successfully constructed a resistor-loaded unipolar inverter with a high gain of 10.76. This study highlights the potential of codoped SnO₂ TFTs for advanced applications in electronic devices.