Study On Fabrication And Electrical Properties Of Physical Transient Resistive Memories Based On ZnO

Resistive random access memory（RRAM）has been attracting more and more attention because of its simple structure,fast read/write speed,low power consumption,low cost,high scalability and good compatibility with Complementary Metal Oxide Semiconductor process.On the other hand,degradable electronics have been increasingly researched and discussed as electronic waste is increasing year by year and security of information storage is getting more and more attention.Physical transient resistive memory,which combines the advantages of both non-volatile resistive memory and degradable electronics,has become a hot topic in related research.In this paper,physical transient resistive switching memories were fabricated as zinc oxide（ZnO）thin films were used as the dielectric layer and silk fibroin（SF）thin films were used as substrates to realize the function of physical transient due to its water solubility.In this thesis,we investigated the resistive switching characteristics and the conductivity mechanism of several devices with different structures.The main contents and conclusions are as follows:（1）In this work,ZnO thin films were prepared by sol-gel method and were used as the dielectric layer of Ag/ZnO/Au device.The experimental results show that the Ag/ZnO/Au device exhibits typical bipolar resistive switching behavior with the scanning voltage of-0.5～0.5 V,.However,the endurance performance of the device were not stable enough.Therefore,we switched to magnetron sputtering to fabricate ZnO films and annealed them at different temperatures（without annealed,50℃,150℃,250℃,350℃and 450℃）to investigate the electrical properties of the Ag/ZnO/Au devices.the results show that all devices exhibited typical bipolar resistive switching behavior,and compared to the former,their ratios of R_HRS/R_LRS and stability of the devices were improved.（2）In order to fabricate physical transient devices,water-soluble SF films are used as substrates for the device.Since the molecular structure of SF would be destroyed while the temperature exceeds 170°C,the devices need to be fabricated at low temperatures.Based on the above experimental findings,it is clear that the ZnO films fabricated by magnetron sputtering have good characteristics of resistive switching with ZnO films annealed at low temperature.Therefore,in this work,ZnO thin films were annealed at low temperatures（50～150°C）.The electrical properties of Ag/ZnO/Au/SF devices showed that the device annealed at 125°C had the best characteristics of bipolar resistive switching with a radio of R_HRS/R_LRS of 42,fatigue resistance of more than 200 cycles,and retention time of more than 1000 s.The conducting mechanism of the high and low resistance states of the device follows the Space Charge Limited Conduction（SCLC）mechanism.（3）In this work,Ag/ZnO/SF/ITO device was fabricated with ZnO film and SF film as dielectric layers.and the results show that the device exhibits typical bipolar resistive switching behavior with the scanning voltage of-1.6～1.6 V,and has steady resistances of HRS and LRS during more than 110 switching cycles,and more than 1600 s of retention time proves the good non-volatile properties of the device.The conductive mechanism of the device is the SCLC mechanism.