Barium oxide write-once read-many-times memory with a high resistance window

Abstract

The write-once read-many-times (WORM) memory characteristics of barium oxide (BaO_x) were demonstrated in this study. A BaO_x resistive switching (RS) layer was prepared by a sol–gel process, resulting in a Ba : O atomic ratio of 1 : 2 and a polycrystalline structure. For device fabrication, the top electrodes were Ag and Al, while the bottom electrode was n⁺-Si. WORM memory features were observed in both Ag/BaO_x/n⁺-Si and Al/BaO_x/n⁺-Si devices. However, during the data retention test, a continuous decrease in the OFF-state resistance with increasing time was observed with the Ag/BaO_x/n⁺-Si device. Faster degradation was seen when the device was under a constant voltage stress. In contrast, the Al/BaO_x/n⁺-Si device showed superior data storage stability in both the retention and stress tests. Measurements were conducted at an elevated temperature of 85 °C to confirm the reliability of the results. The data in the Al/BaO_x/n⁺-Si device can be read with a low voltage of 0.2 V, and a high resistance window of 10⁷ remained unchanged for more than 10⁴ s. This is the first study proposing WORM characteristics for barium oxide. In addition, the memory capacities of these devices were higher than those of other metal oxide-based WORM devices reported in the literature.