Degradation of InSnZnO Thin-Film Transistors Under Negative Bias Stress

Degradation of InSnZnO thin-film transistors (TFTs) under negative bias stress (NBS) is systematically studied in this work. A two-stage degradation behavior is observed for the first time. Utilizing TCAD simulations, a degradation model is introduced, in which the first stage of ON current (
${I}_{\text {on}}$
) increase is dominated by an electron concentration increase resulting from energy band bending and
$\text{H}_{{2}}\text{O}$
ionization while the second stage of
${I}_{\text {on}}$
decrease is dominated by an HC effect caused by the extra carriers and NBS-induced lateral electric field. Furthermore, the model is verified by a low-frequency noise measurement.