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 × 2 × 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 N2 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 N2 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.