Effect of Self-Assembled Monolayers (SAMs) as Surface Passivation on the Flexible a-InSnZnO Thin-Film Transistors

To overcome the environment susceptibility of flexible amorphous InSnZnO (a-ITZO) thin-film transistors (TFTs), a surface passivation method utilizing
${n}$
-octyltriethoxysilane (OTES) self-assembled monolayers (SAMs) is developed. The electrical characteristics of the developed transistors indicate that device performance can be enhanced upon OTES passivation, exhibiting high mobility (~19.4 cm
²
V
⁻¹
s
⁻¹
), a steep subthreshold slope (~90 mV/dec), near-zero threshold voltage (~0.6 V), and high ON– OFF current ratio (
$\sim 7.9\times 10^{{{9}}}$
). The passivation layer can effectively improve the stability of flexible ITZO TFTs even under positive bias stress (PBS) and negative bias stress (NBS), and only 0.8/1.3 V threshold voltage shifts are shown after PBS/NBS. In addition, the OTES-passivated transistors exhibit good mechanical reliability and maintain its electrical characteristics during the 10-k bending period, without drastic decline. These results demonstrate that the SAM passivation method is suitable for the fabrication of flexible high-performance metal–oxide electronic devices.