Post-annealing effect on the resistive switching properties of tantalum pentoxide thin film
陳迺澐1*, 胡裕民1
1Applied of Physics, National University of Kaohsiung, Kaohsiung, Taiwan
* presenting author:Nai Yun Chen,
In the past decade, a variety of binary oxide thin films exhibiting resistive switching phenomena have attracted much attention as promising materials for the resistive random access memory (RRAM). Among them, tantalum pentoxide (Ta₂O₅) is extensively studied due to its attractive properties not only for ReRAM but also in dielectric films and anti-reflection coatings. In this work, we have prepared Ta₂O₅ thin film by using a magnetron sputtering method on n-type conducting silicon substrate at room temperature. For comparison, the as-deposited film was cut and then annealed by rapid thermal annealing at 900 °C for 5 minutes. X-ray diffraction results showed that the as-deposited and post-annealed Ta₂O₅ thin films are amorphous and polycrystalline, respectively. Bipolar resistive switching (RS) behavior has been observed in the Au/Ta₂O₅/n-type Si (metal/insulator/semiconductor, MIS) film device samples. In particular, the polycrystalline Ta₂O₅ based MIS device exhibits a larger on/off resistance ratio, higher endurance, and lower set/reset voltages for the MIS samples. By fitting the J-E curves and examining the temperature dependence of I-V curves, we concluded that the electrical conduction mechanisms of the MIS devices in high and low resistance states are Schottky emission and metal-like ohmic conduction, respectively. Besides, x-ray photoemission spectroscopy results suggested that oxygen vacancies would accumulate at the Au/Ta₂O₅ interface when the MIS device is set into a low resistance state. The results clearly demonstrate that post-annealing Ta₂O₅ thin film may improve and also stabilize the RS properties of Au/Ta₂O₅/n-type Si MIS device, and that Ta₂O₅ thin film is a promising material for the next generation of nonvolatile memory device.

Keywords: resistive switching, post-annealing, xps, tantalum pentoxide