Experimental and theoretical analysis of degradation in Ga ₂O₃-In₂O₃-ZnO thin-film transistors

Degradation of Ga₂O₃-In₂O₃-ZnO (GIZO) thin-film transistors (TFTs), which are promising for driving circuits of next-generation displays, was studied. We evaluated degradation caused by applying gate voltage and drain voltage stress. A parallel shift of the transfer curve was observed under gate voltage stress. The amount of threshold voltage shift when applying gate and drain voltage stress was smaller than that in the case of only gate voltage stress. Joule heating caused by the drain current was observed. We reproduced this degradation of transfer curve change by device simulation. When we assumed the trap level as the density of state (DOS) model and increased two kinds of trap density, we obtained properties that show the same trends as the experimental results. We concluded that two degradation mechanisms occur under gate and drain voltage stress conditions.