Research On Construction And Properties Of ZnO-Based Transparent RRAM Devices

As the rising technologies of artificial intelligence and Big Data,as well as the technical bottleneck of traditional flash memory,it has become more and more urgent to develop new nonvolatile memory.On the other hand,an increasing number of transparent electronic products were pouring into the market.Resistive Random Access Memory(RRAM)is one of the most potential storage technologies in many new nonvolatile memories because of its many advantages such as good scalability,fast write/read speed,and low power consumption.The transparent resistance random access memory(TRRAM),which has high transparency in the visible region,was becoming a new area of research.The performance of resistance random access memory heavily depended on its materials.In this paper,ITO was used as electrode material and Zn O was choosen as middle layer.High-k material of HfO_x was used as insertion layer as well.Single-layer and bilayer ZnO-based transparent resistance random access memory devices were fabricated.ITO thin film was optimized for high transmittance and conductivity.The influence of ZnO thin film deposition process such as sputtering power and differernt oxygen pressures on the performance of single-layer ZnO transparent RRAM was analyzed.Then its performance in illumination environment was studied.Finally,the influences of the thickness of HfO_x to the low-power-consumption ZnO-HfO_x transparent RRAM devices were analyzed.1.Different oxygen pressure mainly affected the initial resistive ratio of the devices.When the oxygen partial pressure was 20%,the device performed the best and the initial resistive ratio was above 10~3 orders of magnitude.With the improving of substrate temperature,forming voltage was descend as well as initial resistive ratio.The sputtering power had a great impact on the endurance of the transparent RRAM devices.When the sputtering power was 120 W,the endurance could reach 10~3 cycles,almost twice more than others.Through the linear fitting of I-V curve,it was shown that the conduction mechanism of ITO/ZnO/ITO transparent RRAM device in low resistance was ohmic conduction mechanism,while in high resistance state the conduction mechanism was Schottky emission echanism.2.By testing in monochromatic light illumination,the initial resistive ratio of the transparent RRAM device was slight improved by 5%.In addition,the uniformity of the switching voltage was improved and the endurance was almostly double as the device without illumination.3.The structure of ITO/ZnO/HfO_x/ITO and ITO//HfO_x/ZnO/ITO were fabricated and the effect of HfO_x thickness on the TRRAM was investigated.The bilayer TRRAM was provided with low power consumption characteristic.Finally the TRRAM resistive switching mechanism of high and low resistance was governed by the SCLC mechanism and oxygen vacancy conductive filaments,respectively.