On the origin of enhanced resistive switching behaviors of Ti-doped HfO2 film with nitrogen annealing atmosphere

In this work, the resistive switching (RS) characteristics of Ti-doped HfO2 under different doping concentration and annealing condition were theoretically investigated by using the first-principles calculation method. For a 2 x 2 x 2 HfO2 supercell, the formation energy of an oxygen vacancy (Vo) reaches the minimum when three Hf atoms were substituted by three Ti atoms. Based on the 3-Ti-doped HfO2 supercell model, numerical results show that low oxygen partial pressure, high annealing temperature and N-2 annealing atmosphere would lead to a low Vo formation energy. By calculating the migration energy of a Vo, we found that the Vo tends to migrate near and towards the Ti dopants. The concentration of Vo and N-2 annealing atmosphere are also beneficial for the connection of conducting filaments. Our numerical results show reasonable agreement with previous experiment about the RS performance of ITO/Ti:HfO2/Pt device.