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

Abstract

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 H2O. 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.