Enhancement in Positive Bias Stress Stability of In-Ga-Zn-O Thin-Film Transistors with Vertically Graded-Oxygen-Vacancy Active Layer

摘要

To enhance the bias stability of amorphous indium gallium zinc oxide (a-IGZO) thin-film transistors (TFTs), we proposed a simple method to deposit the vertically graded-oxygen-vacancy active layer (VGA). The oxygen partial pressure was varied during deposition in order to fabricate VGA TFTs using sputtering. By adopting this method, we could control the concentration of oxygen vacancy in active layer according to the depth. The threshold voltage shift of optimized VGA TFTs was drastically improved under positive bias stress (PBS) condition compared with conventional ones.