미래를 창조하는 포스텍 화학공학과
We elucidate how non-destructive sublimation-doping of In2O3/ZnO heterojunctions with various amidine-based organic dopants affects the degree of band bending of the heterojunction and thus the overall performance of solution-processed heterojunction oxide thin-film transistors (TFTs). Ultraviolet photoelectron spectroscopy and X-ray photoelectron spectroscopy analyses show that the stronger the basicity of the dopant, the smaller the EC − EF of ZnO that can be induced within a short doping time, resulting in a high electron mobility due to the increased electron density of the In2O3 layer at the vicinity of the heterointerface. Mott–Schottky analysis combined with secondary ion mass spectroscopy shows the preferential modification of EC − EF selectively for the ZnO layer. The use of a super base with the highest basicity exhibits a high electron mobility of 17.8 cm2 V−1 s−1 for the SiO2 and 37.8 cm2 V−1 s−1 on average (46.6 cm2 V−1 s−1 maximum) for the ZrO2 dielectric layers and enhanced operational bias-stress stability via sublimation-doping for 6 min, which can be attributed to the trap-filled, percolation-limited charge transport behavior. Reproducibility tests are conducted for more than 50 independently fabricated TFTs using the optimized doping technique, and electron mobility distributions with deviations <±10% are demonstrated. This study shows that sublimation doping with super bases can be a good solution for high mobility oxide TFTs with stability and reliability.