Threshold Voltage Instabilities in Perpetual Switching of Low-Voltage Thin-Film Transistors with Solution-Processed In2O3 Channel Layer

Thin-film transistors (TFTs) with solutionprocessed indium oxide (In
₂
O
₃
) as the channel layer and with aluminium oxide as the gate dielectric were fabricated. The fabricated In
₂
O
₃
TFTs are tested for reliability in low-voltage operation. Measurement results show that the threshold voltage (V
_th
) increases from 0.6 V to 1.4 V under positive bias stress (PBS) and decreases from 0.55 V to 0.22 V under negative bias stress (NBS). Upon relaxation for long enough time, Vth restores close to the pristine values. When switching the In
₂
O
₃
TFTs repeatedly by applying a pulsed voltage of ±3V to the gate, the Vth shift (ΔVth) depends on the pulse width. While ΔVth generally decreases with the pulse width under pulsed NBS, Vth instability is considerably worse under pulsed PBS, particularly when the pulse width is between 5 μs and 50 ms. Apart from revealing the differences in the trapping and de-trapping of electrons and holes at the In
₂
O
₃
/Al
₂
O
₃
interface, the results have implications for using the In
₂
O
₃
TFTs in circuits in which they are biased or switched repeatedly.