The Effect of Oxide and Nitride Passivation on the Behavior of In-Ga-Zn-O Thin-Film Transistors under Negative and Positive Bias Illumination Stress: A Photo-excited Charge Collection Spectroscopic Analysis

Abstract

Two different types of In-Ga-Zn-O thin-film transistors, each passivated with SiO(x) and SiN(x), were studied under negative and positive bias illumination stress (NBIS and PBIS, respectively). Larger shifts in threshold voltage were observed in the SiN(x)-passivated device under both NBIS and PBIS. Photo-excited charge collection spectroscopy analyses suggest that the incorporation of hydrogen during the nitride deposition induces a larger concentration of sub-bandgap trap sites within the oxide semiconductor and/or at the semiconductor/dielectric interface. These are suspected to trap holes during NBIS and electrons during PBIS, which induce negative and positive shifts in the threshold voltage, respectively.