Sr:F co-doping of In2O3 thin film and its dual inhibition effect on trap states to achieve a high stability thin film transistor deposited by solution process

Abstract

In the paper, excellent stability for a solution-processed SrInOF thin film transistor (TFT) device has been achieved by an ingenious Sr:F co-doping route, which is attributed to the dual inhibition effect on the trap states in the SrInOF system. The metal Sr cations exhibit a stronger binding dissociation energy for Sr–O than for In–O, while the F anions present a similar ionic radius compared to oxygen, which results in a strong suppressive effect on the trap states in the SrInOF system and leads to superior stability. The optimized ΔVTH under the negative bias-illumination stress (NBIS), positive bias stress (PBS) and temperature effect are −0.7 V, 0.8 V and −1.2 V for the superior SrInOF TFT device, compared to −11.6 V (NBIS), 8.1 V (PBS) and −8.0 V (temperature effect) for the initial In2O3 TFT, respectively. Furthermore, F anions can simultaneously substitute for oxygen atoms in the lattice, releasing a free electron to the conduction band, which can enhance the electrical performance of the SrInOF TFT. The µ, VTH, SS and Ion/Ioff for the optimized SrInOF TFT are 14.1 V−1 s−1, 1.51 V, 0.22 V/dec and 2.66 × 107, which fully meets the operational need for TFTs in flat panel displays. It implies that Sr:F co-doping is the perfect method to enhance TFT stability and their electrical performance.