Chemical bonds in nitrogen-doped amorphous InGaZnO thin film transistors

Abstract

We investigated the chemical bonds in nitrogen-doped amorphous InGaZnO (a-IGZO:N) thin films with an X-ray photoelectron spectrometer (XPS). The doped nitrogen atoms preferentially combined with Ga cations and formed stable GaN bonds for low nitrogen-doping (N-doping), but additionally formed less stable InN and ZnN bonds for high N-doping. The stable GaN bonds and few defects made the variation in oxygen vacancy (VO) more difficult and hence achieved better stability of thin film transistors (TFTs) with low doped a-IGZO:N channel layers. Contrarily, the less stable InN and ZnN bonds as well as excess defects led to an easier change in VO and thus more unstable a-IGZO:N TFTs for high N-doping. Keywords: Amorphous InGaZnO (a-IGZO), Thin film transistors (TFTs), Nitrogen doping (N-doping), Chemical bonds