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Daejeon, South Korea

Bak J.Y.,Kyung Hee University | Yang S.,Kyung Hee University | Yang S.,Oxide TFT Research Team | Ryu M.K.,Oxide TFT Research Team | And 3 more authors.
ACS Applied Materials and Interfaces | Year: 2012

The effects of electrode materials on the device stabilities of In-Ga-Zn-O (IGZO) thin-film transistors (TFTs) were investigated under gate- and/or drain-bias stress conditions. The fabricated IGZO TFTs with a top-gate bottom-contact structure exhibited very similar transfer characteristics between the devices using indium-tin oxide (ITO) and titanium electrodes. Typical values of the mobility and threshold voltage of each device were obtained as 13.4 cm 2 V -1 s -1 and 0.72 V (ITO device) and 13.8 cm 2 V -1 s -1 and 0.66 V (titanium device). Even though the stabilities examined under negative and positive gate-bias stresses showed no degradation for both devices, the instabilities caused by the drain-bias stress were significantly dependent on the types of electrode materials. The negative shifts of the threshold voltage for the ITO and titanium devices after the 10 4-s-long drain-bias stress were estimated as 2.06 and 0.96 V, respectively. Superior characteristics of the device using titanium electrodes after a higher temperature annealing process were suggested to originate from the formation of a self-limiting barrier layer at interfaces by nanoscale observations using transmission electron microscopy. © 2012 American Chemical Society.

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