Dual-source device architecture for self-diagnosis and correction of gate bias-stress instability in flexible transparent ZnO thin-film transistors

Abstract

Flexible transparent ZnO thin-film transistors (TFTs) have gained momentum during the last decade because of the increasingly emerging demands in flexible transparent displays and wearable electronics industry. However, the instability issue regarding a deviation of turn-on voltage under gate bias stress has remained unsettled, greatly impeding the progress towards practical applications. Here we present a solution to this problem by adopting a new dual-source device architecture to self-diagnose and pull back the deviated turn-on voltage. The dual-source TFTs were fabricated on PEN substrate by conventional UV photolithography with ZnO channel prepared by magnetron sputtering technique. By combining the presented device architecture with a rapid correction process, the turn-on voltage shift was reduced to 0.1 V under −15 V gate voltage bias stress of 5000 s, which favors low power consumption circuits by preventing the TFTs drifting from enhancement to depletion mode. To illustrate its unique working mechanism, device physics simulation, square-law model deduction and circuit current analysis were carried out. The methodology we developed enhances the stability of flexible transparent oxide TFTs and can be adapted in other microelectronic and optoelectronic devices.