A Study Of The Resistive Switching Performance Based On Gallium Oxide Thin Film

As one of the next-generation nonvolatile memory ideal candidates, RRAM with simple device structure, low power consumption, fast switching speed, and high density integration, and the other unique outstanding performance has got more and more attention. Negative differential resistance（NDR） has attracted intensive attentions due to the characteristics of multi-value storage. This novel NDR effect has been observed in many material systems, including double-barrier structures, GaAs-AlAs periodic structure, bilayer molecular junction, metal/self-assembled monolayer（SAM）/metal sandwich structure, TiO2/Nb:SrTiO3 structure, CeO2/ZnO/Nb:SrTiO3 stacked heterostructures and BaTiO3 thin film. In order to explain the physical causes of the RS, the researcher has made some theoretical work, Many models have been proposed to explain the NDR behavior. However, there has been no specific experimental data proving the theoretical model, theoretical analysis are also needed to do further research work. Therefore, the important challenge is to construct a correct physical theory model to reveal the transport mechanisms and process of the RS and NDR.We explore the growth process conditions of Ga₂O₃ films by pulsed laser deposition technique（PLD） at first. Then the Au/Ga₂O₃-x/NSTO/Au structure is successfully fabricated. In this thesis, we focus on the effect of different test conditions on the behavior of the RS and NDR, and study the resistive behavior and transport mechanisms of the RS and NDR based on Ga₂O₃-x/Nb:SrTiO3 interface. The main contents and achievements of this paper include the following aspects:First: The influence of substrate temperature, pulse laser frequency, and pulsed laser energy on the growth of Ga₂O₃ thin films were studied by means of pulsed laser deposition. The composition of Ga₂O₃ films was analyzed by XPS and XRD. The surface morphology of Ga₂O₃ films was analyzed by AFM and SEM.Second: Amorphous Ga₂O₃-x film with a thickness of ¹50 nm is grown on（100） Nb:SrTiO3 substrate. Au electrodes are deposited on the thin Ga₂O₃-x film and NSTO substrate using DC magnetron sputtering. The Au/Ga₂O₃-x/NSTO/Au structure was successfully prepared. Then I-V curves and RS storage performances were tested by the Keithley 2400. Bipolar RS behavior and NDR phenomenon were found during the scan test, and the device has a large HRS/LRS ratio and stable performance.Third: The effect of positive voltage and negative voltage on negative differential resistance is analyzed, and the effect of voltage polarity on the device is also studied. According to the related experimental results, it is considered that the RS behavior and the NDR phenomenon of the Au/Ga₂O₃-x/NSTO/Au structure are derived from the Ga₂O₃-x/NSTO interface, which is caused by the charge trapping/detrapping from the oxygen vacancies in the interface. The more charge trapped by oxygen vacancies under the higher the positive bias voltage, and accordingly the higher voltage of the negative differential resistance phenomenon.