M.Sc Thesis

M.Sc StudentEmanuelle Goren
SubjectPreparation Application and cCaracterization of a ReRAM Type
Nonvolatile Memory Device Made of Oxide
DepartmentDepartment of Nanoscience and Nanotechnology
Supervisor Professor Tsur Yoed
Full Thesis textFull thesis text - English Version


Recently, a promising candidate for future non-volatile memory applications has emerged in the form of the resistance random access memory (ReRAM), which can also be described as so-called memristor. This element is based on the resistive switching phenomenon. The phenomenon is the ability to switch the resistance of the device in a reversible manner between two different states either high resistance state (OFF state) or low resistance state (ON state). This is done by applying an appropriate electrical voltage pulse on it. These two states can be translated into a binary code, and therefore a memory cell can be created.

            A ReRAM memory cell typically has a capacitor-like structure, composed of an insulating nanometric layer, sandwiched between two metal electrodes. The ReRAM mechanism is based on interfacial phenomena and/ or bulk‑related phenomena. It can be dominated by either an electronic or ionic conductivity, and can take place within the whole layer bulk volume, or at a confined volume, with the occurrence of a filament which could be turned ON or OFF.

            Producing switchable TiOx based ReRAMs using a low cost chemical fabrication method was established via sol-gel method and compared with devices made by atomic layer deposition (ALD), which is the most common technique today for ReRAM production. Different hysteresis loops were observed in the I-V measurements for each fabrication method, which may imply different physical mechanism. Moreover, the effect of the nanoparticles' layer properties in the resistive switching behavior was studied. Eventually, impedance spectroscopy was performed and Impedance Spectroscopy Genetic Programming (ISGP) was used to find the distribution of relaxation times. This can serve as a powerful tool for deeper understanding of different mechanisms in the resistive switch behavior. Those mechanisms are not yet fully understood and are widely investigated today.