Control of electrical properties in solution-processed ATO thin-film transistors through gallium doping

Abstract

In this study, we investigated the effects of Gallium (Ga) doping on the electrical properties of solution-processed Antimony-Tin Oxide (ATO) thin-film transistors (TFTs). Notably, ATO films initially exhibited no switching characteristics due to their high conductivity. However, doping Ga into ATO successfully induced switching behavior. The Antimony–Gallium–Tin Oxide (AGTO) TFT, with a Ga doping concentration of 20%, demonstrated excellent electrical performance, achieving a saturation mobility of 1.12 cm² V⁻¹ s⁻¹ and an on/off current ratio of 4.68 × 10⁴. Furthermore, the device exhibited stability under both negative and positive bias stress conditions, with threshold voltage shifts of −2 V and +1.8 V, respectively. These results are attributed to the introduction of Ga, which not only reduced the electron concentration by creating holes within the Tin oxide matrix but also decreased oxygen-related defects in the film due to the strong bonding affinity of Ga with oxygen. Additionally, Ga doping suppressed crystallization in the ATO film, thereby contributing to the formation of highly uniform films. Consequently, it was demonstrated that AGTO allows effective control over defects and carrier concentration by adjusting the Ga content. Therefore, solution-processed AGTO is anticipated to be a promising oxide semiconductor for low-cost and large-area applications.