Oxygen vacancy and film crystallization effects on resistive switching behaviors of CuAlOx thin films

The resistive switching characteristics of n-type CuAlOx thin films fabricated by rf magnetron sputtering under different gas-flow ratios of O2/Ar were examined in this study. The dependence of resistive switching on the O2/Ar rate was found. The conduction mechanisms could be described as nearest-neighboring hopping and variable-range hopping conductions. For high or low resistive states (HRS or LRS), the electrical resistance decreases with increasing temperature, indicating semiconducting behavior. The transition from HRS to LRS due to the migration of oxygen vacancies (VO) is associated with electron hopping mediated through the VO trap sites. The findings show the importance of simultaneous control of the number of oxygen vacancies and film crystallinity in achieving optimization of oxide-based memory devices.