Operational stability of solution based zinc tin oxide/SiO2 thin film transistors under gate bias stress

In this study, we report solution-processed amorphous zinc tin oxide transistors exhibiting high operational stability under positive gate bias stress, translated by a recoverable threshold voltage shift of about 20% of total applied stress voltage. Under vacuum condition, the threshold voltage shift saturates showing that the gate-bias stress is limited by trap exhaustion or balance between trap filling and emptying mechanism. In ambient atmosphere, the threshold voltage shift no longer saturates, stability is degraded and the recovering process is impeded. We suggest that the trapping time during the stress and detrapping time in recovering are affected by oxygen adsorption/desorption processes. The time constants extracted from stretched exponential fitting curves are approximate to 10(6) s and 10(5) s in vacuum and air, respectively. (C) 2015 Author(s).FEDER through COMPETE 2020 Programme; European Communities 7th Framework Programme (i-FLEXIS project) [ICT-2013-10-611070]; National Funds through FCT-Portuguese Foundation for Science and Technology [UID/CTM/50025/2013, EXCL/CTM-NAN/0201/2012]