Solution-based Synthesis And Resistive Memory Device Applications Of ZnO-based Thin Films

With the development of information science and technology, especially with the emergences of portable and intelligent devices, cloud computing, cloud storage and high-definition audio and video, the demands of electronic system for storage devices are becoming more and more strict. Storage are already moving towards the direction of operating speed, large capacity, high storage density and low power consumption. But the traditional silicon based storage technologies are gonging to its physical and technologic limits. At the same time, the cost, power consumption and other issues are becoming more serious as the technology advances. Simply relying on the miniature technology is difficult to meet the future technology of silicon memory storage requirements. Phase change memory (PRAM), ferroelectric memory (FRAM), magnetoresistive memory (MRAM), resisitive switching memory (RRAM) and other novel storage technology are attracting more and more researchers to study for their own advantages respectively. Owning to its simple structure, fast operation speed, low power consumption, and compatible with CMOS technology, the resisitive switching memory are considered as the most promising candidate for the next-generation non-volatile memory. ZnO-based thin films is famous for their excellent electrical and optical properties. Recently, their resisitive switching characteristics also were widely reported. But the preparation method, material selection and many other problems of ZnO-based films resistive switching devices have not been explored systemically. So it is very necessary to study the ZnO-based films resistive switching devices, from the preparation to the performance test thoroughly.In this work, the ZnO-based materials were preparated by sol-gel. At the same time, the influence of the stabilizer on the stability of the solution was investigated. The experimental results showed that the excess ethanol amine could improve the stability of the solution and improve the quality of the films prepared by the solution. Silver nitrate and sodium citrate react to from silver citrate. And the silver citrate were used as the precursor of silver,1,2 propylene amine as complexing agent, to prepare silver inks with different solvents. The contrast experiments showed that the silver inks based on the solvent of the mixture of the methanol and the alcohol can form accurate pattern in the ZnO-based films by ink-jet printing.The MIM structure resistive switching devices were assembly, with the ZnO-based thin films as storage medium and the Ag films as electrodes on ITO glass substrate. Acrossding to the Ⅰ-Ⅴ characteristic curve, the forming and rupture of nono-conductive filaments can be responsible for the resistive switching characteristics of Ag/ZnO/ITO, Ag/GZO/ITO and Ag/IGZO/ITO devices. The Ag/IZO/ITO device has no stable switching behaviour.The influence of the IGZO thin films thickness on the behaviour of the Ag/IGZO/ITO devices were studied, by comparing the Ⅰ-Ⅴ curves of the Ag/IGZO/ITO devices with different thickness dielectric. The results showed that the devices forming,’set’ and ’reset’ voltages are all increased as the thickness of the IGZO thin films increasing, and the electrical parameters of the devices also fluctuate more severely. By comparing the Ag/IGZO/Si resistive characteristics with the one on ITO coated glass substrate, the Ag/IGZO/ITO structure devices electrical parameters in the high resistance state fluctuate smaller.Reliability test of unipolar Ag/IGZO/ITO devices exihibited that the original resistances, the resistances on low resistance state and on the high resistance state of the devices on the same substrate are distributed in an acceptable range. The single device test shows that the memory window of Ag/IGZO/ITO device is more than two orders of magnitude. It also exhibited satisfactory performances in the resistance to fatigue sex, data retention and readability...