| Summary: | 碩士 === 國立交通大學 === 電子研究所 === 100 === The resistive switching random access memories (RRAMs) possess some advantages of scalability, low power consumption, fast operating speed and stable endurance. The RRAM with these advantages has high potential for next generation memory applications. We use silicon oxide films doped with rare earth metal Gd as the insulator. The switching mechanism and electrical characteristics of Pt/SiO2:Gd/TiN RRAM devices are investigated by material analysis and electrical measurement system.
The material characteristic of the thin insulator film were analyzed by x-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). Aglient B1500 was used to measure the electrical properties. Some oxygen vacancies were observed in the pristine DMO film through XPS. The low resistance state (LRS) is metal-like and the high resistance state has semiconductor-like properties. From the electric measurement at different temperatures, we found that the endurance of the RRAM can achieve 105 cycles and its retention time can reach 104 seconds
We also found that the doped layer can achieve multilevel for unipolar reset. We compared it with the bipolar multilevel by reset mechanism and current fitting. After current fitting, we extract parameter and set physical model to explain reset behavior for both unipolar and bipolar.
In addition, we added a pure oxide layer on top of the doped layer. We found that the doped layer can act as an oxide reservoir. Because there are two switching layer coexisting complementary resistance switching (CRS) can be made in the double-layer structure. which is simpler in fabrication and can replace a back to back structure.
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