The 15th IEEE International Conference on Electron Devices and Solid-State Circuits (EDSSC)

680 / 2019-05-11 18:55:01

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

indium oxide thin film transistors (TFTs), solution-processed, bias stress, threshold voltage shift, In2O3 TFT

Plenary track > Device and Circuit Reliability

Thin-film transistors (TFTs) with solution-processed indium oxide (In2O3) as the channel layer and with aluminium oxide as the gate dielectric were fabricated. The fabricated In2O3 TFTs are tested for reliability in low-voltage operation. Measurement results show that the threshold voltage (Vth) 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 In2O3 TFTs repeatedly by applying a pulsed voltage of 3V to the gate, the Vth shift (deltaVth) depends on the pulse width. While the Vth shift 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 In2O3/Al2O3 interface, the results have implications for using the In2O3 TFTs in circuits in which they are biased or switched repeatedly.