Evaluation of Positive-Bias-Stress-Induced Degradation in InSnZnO Thin-Film Transistors by Low Frequency Noise Measurement

In this letter, degradation of InSnZnO thin-film transistors (TFTs) under positive bias stress (PBS) is evaluated by low frequency noise (LFN) measurement for the first time. With PBS time, the LFN level and trap state density first decrease and then increase, and meanwhile, the dominant fluctuation model changes from carrier number fluctuation model toward to bulk carrier mobility fluctuation model. By considering the interactions of oxygen vacancies, hydrogens and electrons, a degradation model based on the effect of vertical electrical field and water ionization is tentatively proposed and discussed.