Enhanced Electrical and Mechanical Performance of InSnZnO TFTs With Multifunctional Laminated Organic Passivation Layer

To realize high-performance and stable electrical characteristics for ZnO-based thin-film transistors (TFTs) under various environments, we propose InSnZnO (ITZO) TFTs with multifunctional laminated organic (MLO) passivation layers (PVLs). The MLO PVLs were constructed from self-assembled monolayers (SAMs) and an ultraviolet (UV) light absorber-modified polydimethylsiloxane (PDMS) layer. The SAMs can passivate the ITZO surface and suppress the chemical reaction during the spin-coating process, and the modified PDMS layer can block UV light. The MLO-treated ITZO TFTs exhibited a high-performance and robust stability with high mobility (~21.18 cm2
$\cdot $
V−1
$\cdot $
s−1), a considerable ON– OFF current ratio (~
$6.65\times10$
9), and a steep subthreshold slope (~100 mV/dec). The shift of the threshold voltage (
${\textit V}_{{\mathrm {th}}}$
) under gate bias stress and UV light illumination stress was investigated for the devices with different PVLs. The ITZO TFTs with MLO PVLs showed improved stability under positive gate bias stress (PBS), positive gate bias illumination stress (PBIS), and negative gate bias illumination stress (NBIS) compared to untreated and SAM-treated ITZO TFTs. Furthermore, the MLO-treated ITZO TFTs achieved a weak response to 365-nm UV light and showed superb stability with the negligible change of electrical performance, even after a 1-h water soaking test and a 100-day storing test. In addition, the MLO PVL exhibited high flexibility without signs of cracking even after 10 000 bending cycles and was proven suitable for fabricating flexible oxide TFTs.