The Fabrcation And Resistive Switching Properties Of TiO₂ Films By Pulsed Laser Deposition

The resistance random access memory（RRAM）, as one of the most potential techniques for the next generation non-volatile memories, has attracted increasing attention in the last decades. The switching properties and mechanisms of resistive switching materials, which play important role on the performance RRAM, have been intensively investigated. In this thesis, TiO₂ was deposited by pulsed laser deposition（PLD） under different fabrication parameters, including various substrate temperatures, laser energies, deposition pressures and annealing pressures. Current-voltage（I-V） measurement has been carried out to study the resistive switching properties of TiO₂. The resistive switching mechanism was also discussed by X-ray photoelectron spectroscopy and I-V curve fitting.（1） Firstly, TiO₂ thin films were deposited by PLD on Pt/Ti/SiO2/Si substrate to form metal-insulator-metal（M-I-M） structure in this thesis. The influence of oxygen pressure, temperature and laser energy on the structure and the performance of resistive switching（RS） of TiO₂ thin film were researched by XRD, SEM, AFM and so on. According to the I-V curves and the ratio between the high resistance state（HRS） and the low resistance state（LRS）（RHRS/RLRS）, TiO₂ sample deposited at 600 ℃ substrate temperature, 150 mJ laser energy and 10 Pa oxygen pressure, which is the optimal deposition parameter, showed the highest RHRS/RLRS（¹000）..（2）Secondly, the RS properties of TiO₂ thin film can be further improved by in-situ annealing. I-V measurement of TiO₂ films deposited using the above optimal parameters were annealed under different oxygen pressures. It was found that I-V curves of TiO₂ showed RHRS/RLRS ratio as high as 50000. And it can remain the origin I-V curve after scanning 1500 loops, indicating an excellent retention property.（3） Finally, the conducting mechanism of TiO₂ thin film by testing I-V curves of TiO₂ films with different electrode areas and various temperatures. It was find that the resistive switching property of TiO₂ was result from space-charge-limited-current and Schottky emission model according to the I-V curves and fitting results.In summary, TiO₂ resistive switching film has been fabricated by PLD and its performance has been improved by optimal the deposition and annealing parameters. The interface type resistive mechanism makes TiO₂ thin film show good consistency, which is an essential factor for RRAM devices.