Improved Switching Uniformity of SCLC-RRAM Using the Vertically Formed Nanoscale 2DEG Electrode and Control of Oxygen Vacancy Distribution

In recent years, many studies have focused on addressing the switching variability of filamentary switching resistive random access memory (F-RRAM). This problem persists owing to the inherent unpredictability in the formation and rupture of filaments during the resistive switching process. In this study, we developed a method for using space charge limited current (SCLC) switching-based RRAM (S-RRAM) in a highly scaled cell area by revealing the changes in the switching mechanism of TiO2-based RRAM based on the oxygen vacancy (V-o) concentration. Experimental results revealed that the vertically oriented two-dimensional (2D) electron gas (V-2DEG) electrode significantly minimized the device cell area to 300 nm(2). This, in turn, facilitated a precise manipulation of the V-o concentration in TiO2 via thermal migration of V-o during the annealing phase. Consequently, an S-RRAM with excellent switching characteristics was implemented under the condition of rapid thermal annealing (RTA) at 300 degrees C for 1 min. The S-RRAM device, driven by electron trapping and detrapping at the V-o trap site, exhibited outstanding switching uniformity, a reduced operating voltage (<1 V), and a substantial on/off ratio (>40). The impressive switching performance and area scalability of the S-RRAM afforded by the V-o concentration-controllable V-2DEG electrode configuration hold significant potential for future high-density nonvolatile memory applications.