The Nature of the Oxygen Vacancy in Amorphous Oxide Semiconductors: Shallow Versus Deep

Using first‐principles calculation, we investigate the nature of oxygen vacancy ( V O ), namely shallow versus deep, in the amorphous oxide semiconductor InGaZnO 4 ( a ‐IGZO), which has not been fully clarified despite its technological importance. Oxygen‐deficient amorphous models are generated through the hybrid functional molecular dynamics (MD) simulations that allow for finding stable V O configurations while minimizing computational approximations. From eight independent models, we consistently find that V O serves as the shallow donor, increasing the Fermi level above the conduction band minimum. For comparison purpose, we also generate deep V O models by charging the system during MD simulations. It is found that deep V O is higher in the formation energy than shallow V O , confirming that shallow V O is the preferred type of oxygen vacancies in a ‐IGZO.