Long-Term Aging of Al2O3 Passivated and Unpassivated Flexible a-IGZO TFTs

Amongst the new materials studied for the fabrication of high-performance flexible thin-film transistors (TFTs), amorphous indium-gallium-zinc-oxide (a-IGZO) exhibits a combination of advantages that enables its application in commercial electronics. Hence, it is crucial to understand the electrical stability of a-IGZO TFTs over long periods of time. In this work, we present the effects of long-term aging on Al
₂
O
₃
passivated and unpassivated flexible a-IGZO TFTs over a period of 80 months (
$\approx 6.5$
years). It is found that although remaining functional, these devices are influenced by different instability effects. More specifically, positive gate bias stress experiments indicate that the Al
₂
O
₃
passivation layer contributes to the degradation of the devices’ performance. These results show that the Al
₂
O
₃
passivation, although beneficial to the initial device stability, does not prevent the degradation of the passivated devices in comparison with their unpassivated counterparts after long periods of storage.