Oxygen vacancy defects in Ta2O5 showing long-range atomic re-arrangements

The structure, formation energy, and energy levels of the various oxygen vacancies in Ta2O5 have been calculated using the lambda phase model. The intra-layer vacancies give rise to unusual, long-range bonding rearrangements, which are different for each defect charge state. The 2-fold coordinated intra-layer vacancy is the lowest cost vacancy and forms a deep level 1.5 eV below the conduction band edge. The 3-fold intra-layer vacancy and the 2-fold inter-layer vacancy are higher cost defects, and form shallower levels. The unusual bonding rearrangements lead to low oxygen migration barriers, which are useful for resistive random access memory applications. (C) 2014 AIP Publishing LLC.