Microscopic and spectroscopic analysis of the nature of conductivity changes during resistive switching in silicon-rich silicon oxide
Redox-based resistive random access memory (RRAM) has the scope to greatly improve upon current methods of data storage, despite incomplete understandings of material switching mechanisms. We make use of atomic force microscopy (AFM), conductive atomic force microscopy (cAFM) and X-ray photoelectron spectroscopy (XPS) to characterise the physical processes occurring in the changes in conductance state in silicon-rich silicon oxide RRAM. Surface analyses of the insulating oxide layer of our devices are employed to establish the chemical and structural properties of pristine and switched states. The removal of oxygen from the active layer is observed to be concomitant with the appearance of varying degrees of surface distortion and regions of high conductivity in an otherwise-insulating material. These results support the currently-recognised model of a resistive switching mechanism that is reliant upon the migration of oxygen ions under an electrical bias. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)