Enhanced electrical stability in IGZO TFTs through passivation effects of PTFE in the back-channel layer

Abstract

This research proposes a selective polytetrafluoroethylene (PTFE) doping strategy to enhance the electrical stability of indium gallium zinc oxide (IGZO) thin-film transistors (TFTs). In contrast to conventional single-layer PTFE-doped IGZO TFTs, which increase electrical stability but face a trade-off with reduced mobility due to the uniform distribution of PTFE throughout the layer, this strategy confines PTFE to the back-channel region of the IGZO layer. By preventing PTFE from entering the effective channel where electron transport occurs, mobility loss is minimized, and stability is significantly improved. Compared to conventional IGZO TFTs, the proposed approach reduces threshold voltage shifts under positive bias stress from 4.94 to 2.69 V and under negative bias illumination stress from 16.63 to 10.84 V, all without mobility degradation. The localized PTFE in the back-channel acts as a passivation layer, reducing interactions with oxygen and moisture in the environment. This selective doping approach provides an effective solution for improving the performance and stability of IGZO-based TFTs in advanced display technologies.