The kinetics of the switching process in Cu–SiO2-based electrochemical metallization memory cells was investigated as a function of the switching voltage and the SiO2 film thickness. We observe an exponential dependence of the switching rate on the switching voltage and no significant thickness dependence in the range from 5to20nm SiO2. We conclude from our data that the cathodic electrodeposition represents the rate-limiting step of the switching kinetics. The voltage-time dilemma seems to be overcome by the exponential dependence of the switching rate in combination with a threshold voltage presumably originating from a nucleation overpotential.

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Different coplanar Pt∕Ag structures were prepared by photolithography on SiO2 substrates, and Pt∕H2O∕Ag cells were formed by adding de-ionized H2O to the coplanar Pt∕Ag structures. The Pt∕H2O∕Ag cell is utilized here as a model system, due to the feasibility of visual inspection of the switching process. Bipolar switching was achieved for the cell. Scanning electron microscopy (SEM) investigations demonstrated that the growth and dissolution of Ag dendrites are responsible for the resistive switching. The Ag dendrite morphology is proposed to be the origin of the asymmetrical dissolution during the switching-off process, hence the bipolar nature of the switching characteristics.

Resistive switching in Ir∕SiO2∕Cu memory cells was investigated. The proposed switching mechanism is the formation and dissolution of a Cu filament. Under positive bias, Cu cations migrate through SiO2 and are reduced at the counterelectrode forming a filament. The filament is dissolved under reverse bias. The write current can be reduced down to 10pA which is four orders of magnitude below published values and shows the potential of extremely low power-consuming memory cells. Furthermore, a comparison of the charge flow in the high resistance state and the energy for writing is given for write currents between 25pA and 10nA.