Study On Preparation And Properties Of Modified TiO₂ Based Resistance Switching Memory

Although the rapid development of modern information technology has greatly changed people's life style,it faces severe challenges.It is urgent to develop the next generation of non-volatile storage technology.Among various materials with resistive switching behavior,binary metal oxides have attracted wide attention due to their simple structure,low power consumption,high switching ratio,fast erasing speed,long retention time and compatibility with semiconductor technology.A traditional semiconductor material,titanium dioxide?TiO₂?,has a common resistive switching mechanism?migration of oxygen ions?or oxygen vacancies??,but it is still extremely necessary to improve its resistance performance.In this paper,therefore,non-metallic doping and intercalation were applied to improve the resistive switching charaeterics of TiO₂ film,and the potential physical mechanisms were discussed.The main conclusions are as follows:?1?A series of graphene oxide?GO?doped TiO₂ thin films?TiO₂:GO films?were successfully prepared on ITO glass substrates using spin-coating technology.Ag/TiO₂:GO/ITO devices were fabricated using Ag as the top electrode.The results of XRD?X-ray diffraction?,SEM?scanning electron microscopy?and EDS?energy dispersive spectrometer?measurements show that both the as-prepared TiO₂ and TiO₂:GO films are anatase structure,but the latter retards the crystallization of the films due to GO doping,and the average size of the films increases due to GO coating on the surface of some TiO₂ particles.Compared with Ag/TiO₂/ITO devices?the resistance ratio is about 13?,the resistance ratio of Ag/TiO₂:GO/ITO devices increases to 282 times,the switching voltage dispersion decreases,and the retention and fatigue characteristics also increase significantly.The results of I-V curve fitting in the low resistance?LRS?show that the resistive process of Ag/TiO₂/ITO devices is controlled by both the Schottky barrier and filament mechanism,while the resistance behavior of Ag/TiO₂:GO/ITO devices conforms to the conductive filament mechanism.?2?A series of N-doped TiO2 films?TiO2:N films?were successfully prepared on ITO glass substrates by spin-coating technology,and Ag/TiO2:N/ITO devices were fabricated using Ag as the top electrode.The results of XRD,SEM and XPS show that the as-prepared TiO2:N films have anatase structure,in which the crystalline quality of TiO₂:N-2 thin films?N doping is 30%?is better and the particle size is more uniform.The XPS?X-ray photoelectron spectroscopy?indicates that formation of Ti-N-O bond,suggesting N doped into the TiO2 film.Compared with Ag/TiO2/ITO devices,the resistance ratio of Ag/TiO2:N/ITO devices increases to133 times,and the dispersion of switching voltage is reduced.This may be due to the fact that the formation of Tix?O,N?compounds,produced by interposition doping of N,in the TiO2:N film effectively eliminate the barrier at the interface of TiO₂:N/ITO,and some N reacts with Ti to form TiN nanoclusters,which is more conducive to the formation of conductive filaments.?3?The GO thin films were prepared by spin-coating method,and it was inserted at the interface of Ag/TiO₂:N and TiO₂:N/ITO to study the influence on the resistive switching behaviors of TiO2:N.The results show that the resistive switching performance of both the Ag/GO/TiO2:N/ITO and Ag/TiO2:N/ITO devices are significantly improved compared with those of Ag/TiO₂/ITO devices,especially the resistance ratio of the former increases to 860 times and the switching voltage(V_Set/V_Reset)reduced to±0.57 V.This may be due to the introduction of GO,which greatly increases the oxygen vacancy concentration in the TiO₂:N film.It is the high oxygen vacancy concentration that eliminates the interface barrier between TiO2:N/ITO and is more conducive to the formation of thick conductive filaments in the film.