| Resistive random access memory (RRAM) is one of the most promising candidates for next-generation non-volatile memories (NVM) due to its simple sandwich structure, high storage density, high writing/erasing speed, low power consumption and the CMOS compatibility. For the resistance switching material found, the rare earth doped manganese oxides demonstrate good stability and fatigue. With the anisotropy and reduction of dimensions on structure, the magnetic and electric properties have undergone great changes in two-layer pervoskite manganites. The preparation and resistive switching properties in the Pr(Sr0.1Ca0.9)2Mn207films have been researched. The main results as following:1. The pure target of the PSCMO has been synthesized by sol-gel method. The x-ray diffraction data exhibit single orthorhombic two-layer pervoskite manganites with Am2m space group by the Rietveld analysis. The growing in different deposition temperature, deposition distance, oxygen pressure and deposition times on PSCMO thin films have been researched by pulsed laser deposition. The thin film with good crystallization, uniform particles, and low roughness has been deposited on Pt/Ti/SiO2/Si substrate at the deposition temperature of750℃, deposition distance of4cm, and the oxygen pressure of15Pa. With the increasing thickness of PSCMO thin films, the microscopic structure changed from the random orientation to columnar growth, while the color and the reflection wavelength of the absorption peak were changed with the different thickness and crystal orientation.2. The PSCMO thin films of epitaxial grown have been deposited on SrTiO3(STO) substrate in different oxygen pressure. With the increasing oxygen pressure, the lattice constant of these films decreases linearly and the reduction of oxygen vacancies is the main reason for the decrease of the lattice constant. The distribution of the grain on the film prepared in10Pa oxygen pressure has much more homogeneous compared to the other thin films through the analysis of the surface morphology of the samples.3. The metal Ti electrode and PSCMO resistive transition layer have been deposited on the Pt (111) substrate to investigate the influence of the film thickness and 4. microstructure on resistance switching behaviors. For the films with the disordered growth in microscopic, the variations in the thickness have a little influence on the resistive switching properties. But, the resistive switching characteristics of the microscopic of columnar growth have undergone significant changes. The resistances of high-and low-impedance state of the sample were significantly less than the other samples, while the transition voltage, about3.5V, is significantly higher than the other samples. This is because of the columnar growth in the film to conduct easy charge carrier along grain boundaries.5. The metal Ti, Ag and Au electrode and PSCMO resistive transition layer have been deposited on the Pt/Ti/SiO2/Si(100) substrate. The Ti film exhibits the opposite polarities of bipolar resistance switching behaviors with the other samples. The Ti/PSCMO/Pt film shows a positive bipolar resistive switching behavior (PBRS), while the Au/PSCMO/Pt and Ag/PSCMO/Pt films express negative bipolar resistive switching behaviors(NBRS). When the Gibbs free energy of the formation (AG) of the metal oxides (MOx) is lower than that of the oxygen vacancy in perovskite oxides, the junction shows positive bipolar resistance switching, otherwise the junction shows negative bipolar resistance switching. In addition, the resistances of high-and low-impedance state of the Ag/PSCMO/Pt film were significantly smaller than the other two samples, while the transition voltage,3V, in Au/PSCMO/Pt film sample is significantly higher than the other two film samples, about2V. For the endurance and stability, Au/PSCMO/Pt film sample is better than the other two samples, and more suitable for application. |
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