Research On Conductive Mechanisms And Resistance Control Of Titanium Oxide Memristors

Titanium oxide memristor is one of physical realizations of the theoretical memristor. Currently, it is also the hot topics of the research areas which include material science, circuitry and artificial intelligence and so on. The appearance of memristors will possibly change physical basis of the electronic information technology. However, titanium oxide memristor has nanometer size and complex circuitry characteristics, different materials, parameters and mechanisms may have influences on conductive processes of memristors. Though researchers have already made hard effort to study, the clear and definite conclusions are still unavailable. Therefore, the control and application of resistance state of titanium oxide memristors are urgent key problems which must be solved.The paper deeply studies conductive mechanisms and resistance state control method of titanium oxide memristors, which mainly includes:(1)Development status of the frontier domains, such as device manufacture, conductive mechanisms, modeling, simulation and application of titanium oxide memristors are introduced, problems and deficiencies of current researches are induced.(2)The coexistence of dopant drift and tunnel barrier in titanium oxide memristors is proposed, a kind of model which is based on the coexistence of the two mechanisms is then proposed. The coexistence mechanism is tested by model simulations. The study shows that compared with dopant drift or tunnel barrier based conductive mechanisms, the coexistence of the two mechanisms objectively reveal the physical rules of the device conduction. Moreover, it is also the main reason which causes the instability in the conductive behaviors of memristors.(3)Based on the proposed coexistence model, the influences of device and operational parameters on conductive characteristics of titanium oxide memristors are studied. Methods for improving the stability of the device conduction are proposed, so as to provide potential values for manufacturing titanium oxide memristors with excellent conductive performances.(4)In the cases of the dopant drift model, tunnel barrier model and the coexistence model of the two mechanisms, respectively, the methods for controlling the resistance state of titanium oxide memristors are studied. Based on the dopant drift model, a kind of resistance state control circuit which is used for titanium oxide memristors is proposed, the correctness of the circuit is proved by SPICE simulations.(5)Based on the resistance state control method of titanium oxide memristors, a kind of analog filter circuit with adjustable and non-volatile passband is studied. The filter realizes the accurate change of passband in the designed range; it also holds the passband after the power supply is cut off. The proposed filter solves the problem in the traditional analog filter that the change of passband needs the change of circuit structure.(6)Based on the resistance state control method of titanium oxide memristors, a kind of circuit which is used for analog signal encryption and decryption is studied. The designed circuit utilizes the nonlinear conductive properties and charge-memory ability to encrypt and decrypt the analog signals, respectively. It also provides new ideas for the applications of memristors in information security.Finally, the major works and novelties of this thesis are concluded, some advices for our future work are given.