H2O Induced Hump Phenomenon in Capacitance–Voltage Measurements of a-IGZO Thin-Film Transistors

Through employing capacitance-voltage (C-V) measurements, the stability of a-IGZO TFTs after applying negative bias stress in different ambient atmospheres was investigated. The hump phenomenon in C-V curve, different from that in the vacuum, was observed after applying negative bias stress in the air, which was concerned with H
₂
O. In addition, results in the oxygen atmosphere slightly changed under negative bias stress. Compared with traditional I-V curves, C-V measurements helped to better understand the degradation of a-IGZO TFTs. A two-conductive-way model was built to explain the mechanism of instability.