The role of zinc vacancies in bipolar resistance switching of Ag/ZnO/Pt memory structures

Improvement of the performance in Cr-doped ZnO memory devices via control of oxygen defects

The defect-enhanced resistive switching behavior of Cr-doped ZnO films was investigated in this study, and evidence that the switching effect can be attributed to defects was found. X-ray photoelectron spectroscopy demonstrated the existence of oxygen vacancies in the ZnO-based films, and the concentration of oxygen vacancies in the Cr-doped ZnO film was larger than that in the undoped ZnO film, which can be attributed to Cr doping. We concluded that the defects in Cr-doped ZnO were due to the Cr dopant, leading to excellent performance of Cr-doped ZnO films. In particular, depth-profiling analysis of the X-ray photoelectron spectra demonstrated that the resistive switching effects corresponded to variations in the concentration of the defects. The results confirmed that oxygen vacancies are crucial for the entire class of resistive switching effects in Cr-doped ZnO films. In particular, the Cr-doped ZnO films not only show bipolar resistive switching behavior but also excellent reliability and stability, which should be beneficial for next-generation memory device applications.