Improvement of Negative Bias Stress Stability in Mg0.03Zn0.97O Thin-Film Transistors

A small amount of Mg is introduced into ZnO to form the ternary compound Mg_0.03Zn_0.97O (MZO), which serves as the channel layer of thin-film transistors (TFTs). The MZO TFT shows smaller subthreshold swing of 0.57 V/decade and much better negative bias stress (NBS) stability, which shifts only by -1.21 V in the threshold voltage over its ZnO TFT counterpart (subthreshold swing of 0.79 V/decade; -3.56 V shifts in the threshold voltage after NBS). The superior stability against NBS is mainly attributed to the reduction of donor-like defects associated with ionized oxygen vacancies in the MZO TFT channel.