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

Abstract

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 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> V <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> ), a steep subthreshold slope (-.90 mV/dec), near-zero threshold voltage (-.0.6 V), and high ON- OFF current ratio (-.7.9 x 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">9</sup> ). 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.