||In order to clarify the mechanism of reset process in Ti/HfO2/TiN resistive random access memory (RRAM) devices, constant voltage sampling measurements are carried out at different temperatures. The reset process is dominated by electrochemical first order reaction. Three different values of activation energy are extracted in the reset process, and the corresponding dominant models are proposed in this thesis.|
Transparent conductive film of indium tin oxide (ITO) possesses plenty of benefits over metal electrode, including lower operating current, low set voltage, and self-limiting current characteristic. Therefore, ITO is designed and fabricated as the top electrode, and oxygen ions are verified to be driven into the ITO electrode by current fitting. Moreover, experimental results demonstrate that ITO/SiO2:ITO/TiN devices can exhibit either interface type or filament type resistive switching depending whether forming process is performed. As operating voltage increases, the resistance of the low resistance state decreases, verifying that ITO can be regarded as an oxygen ion reservoir. Besides, the fabricated sample reveals good retention behavior and endurance up to 10^8 times.
In order to make the RRAM devices practical in the future electronic products, complementary resistive switching structure is proposed and fabricated to eliminate the sneak path current in RRAM crossbar array. In this study, due to the property of asymmetric set and reset voltages of ITO electrode, ITO is utilized to realize a larger reading window and minimize the misidentification when compared to that with metal electrodes. Besides electrode pattern designing, the structure of two bipolar RRAM elements antiserially into one complementary resistive switching memory is also fabricated, and can exhibit stable DC sweep cycles up to 1000 times.