**3.1 Formation of a blocking layer on conducting oxides**

The formation of an interface between oxide layer and an active electrode shows significant impact onto the different phenomena such as nonlinear transport of the charge carriers and affects performance of VCM type devices. In particular, the nonstoichiometric metal oxide layer demonstrates reversible oxidation and reduction at or near the interface which makes device functional. It is known that the interface type switching is mainly observed in conducting oxides like doped manganites utilizing metal electrodes e.g. Al, Ti and Ta etc. Such electrode metals exhibit relatively high oxygen affinity facilitating interface driven switching [9, 15, 16]. In case of Pr0.7Ca0.3MnO3 (PCMO), it has been established that the growing Al metal electrode is oxidized whereas deposited PCMO thin film layer depicts the reduction process during deposition process as evidenced by thorough *in-situ* photoemission studies. Therefore, in interface type resistive switching process, the prominent electronic transport across interface is highly dependent upon the developed interfacial oxide thin layer. Such insulating oxide layers at interface are important in deciding the resistivity behavior during switching of the fabricated devices [17]. In TiN/SiO2/Fe stacked structure, Feng *et al.* reported RS behavior induced because of thin FeOx transition layer at SiO2/Fe interface formed

*Effect of Surface Variations on Resistive Switching DOI: http://dx.doi.org/10.5772/intechopen.97562*

during processing of plasma-enhanced tetraethyl orthosilicate. However, after incorporating Pt into Fe electrode (TiN/SiO2/Fe0.73Pt0.27) reduces the concentration of Fe in thin FeOx layer which eventually improved the data dispersion of switching parameters [18]. In another report, the annealing of TiN/SiO2/FeOx/ FePt stratified structure dramatically modifies RS properties. Under optimized annealing conditions, excellent improvements have been observed including distinct reduction in RS parameters such asforming voltage, set/reset voltages, and their dispersions along with higher resistance i.e. ON/OFF ratio [19, 20].
