Multilevel oxygen-vacancy conductive filaments in β-Ga2O3 based resistive random access memory

beta-Ga2O3 has recently attracted considerable attention for its application in resistive switching memory. However, the resistive behaviors and mechanisms of beta-Ga2O3 memory dominated by the oxygen-vacancy (V-O) still remain controversial. In this study, we systemically investigated the formation process of V-O conductive filaments in beta-Ga2O3 memory. There were at least three kinds of V(O)s and conductive filaments with different low resistance states (LRSs) in beta-Ga2O3 memory, suggesting their potential for multilevel storage application. Interestingly, these conductive filaments preferred to be formed along the [010] direction and with a single V-O cluster rather than a mixed V-O cluster due to the lower single V-O cluster formation energy and ellipsoid charge distribution. The lowest migration and activation barriers for different kinds of V(O)s in +2 charge states (V2+Os) were discrepant and lower than the neutral charge states. Meanwhile, the forward migration energy of V-O was different from the reversed migration path, so that the conductive filament formation and rupture were not an inverse process in the experiment. The detailed mechanisms were revealed by the charge density and migration process of these V(O)s. These results not only revealed the function of the V-O conductive filaments in beta-Ga2O3 memory but also predicted the potential of beta-Ga2O3 memory for multilevel storage application.

Automated summary

The study reveals the formation process of V-O conductive filaments in beta-Ga2O3 memory, indicating potential for multilevel storage application. It was found that the conductive filaments prefer to be formed with a single V-O cluster along [010] direction, and different V(O)s exhibit discrepant migration barriers in +2 charge states.