Observation of Divacancy Formation for ZnON Thin-Film Transistors With Excessive N Content

Abstract

This study proposes a model of mobility and negative bias stress stability degradation mechanism of zinc oxynitride (ZnON) thin-film transistors (TFTs) with various anion compositions. The subgap density of states (DOS) for ZnON TFTs were extracted using monochromatic photonic capacitance–voltage measurement. The extracted subgap DOS indicated an additional nitrogen-related subgap peak was observed in ZnON TFTs with an excessive nitrogen condition, which might originate from a nitrogen divacancy formation. Furthermore, the shifted threshold voltage components after the bias stress test were quantitatively divided as subgap DOS and interface trapping.