Lifetime Modeling of ZnO Thin-Film Transistors

A novel method of predicting the lifetime of polycrystalline metal-oxide thin-film transistors (TFTs) is presented. The measured threshold-voltage shift is correlated to the creation of defect (trap) states within the semiconductor grain boundaries. Once this relationship is established, conventional threshold-voltage shift and polycrystalline transport models can be used to predict the TFT current with time. Measured bias-stress data taken from ZnO TFTs fabricated on flexible polyethylene naphthalate substrates are accurately fit using this model.