16.3: AC and DC Bias-Temperature Stability of Coplanar Homojunction a-InGaZnO Thin-Film Transistors

We fabricated coplanar homojunction a-IGZO TFTs that are highly stable under AC and DC bias-temperature-stress. For TFTs of the size W/L = 60μm/10μm, the stress-induced threshold voltage shifts are all within −0.35 V. A comprehensive investigation of AC BTS stress polarity, pulse width, and duty cycle dependence is presented We find that higher frequency of bipolar AC pulses increases the device instability, while lower duty cycle values have the opposite effect.