Contradiction Behaviors between I-V and C-V Curves after Self-Heating Stress in a-IGZO TFT with Triple-Stacked Channel Layers

In this work, an opposite sub-threshold swing trend of I-curve to C-V curve in tri-layer IGZO TFT is observed. Thermal and electrical field effects during stress duration is investigated to clarify this behavior. Results indicate a carrier distribution migration phenomenon; carriers are away from the gate insulator surface after self-heating stress which is caused by defect generations at channel/GI interface. Since carrier tends to locate at the middle layer (In-rich layer) after self-heating stress, carriers away from surface defects leads to a better subthreshold swing in I-V curve. However, C-V curves detects the information of defects leading to S.S degradation.