Switching mechanisms of CMOS-compatible ECRAM transistors—Electrolyte charging and ion plating.

To elucidate the internal chemical physics of measured CMOS-compatible electrochemical random-access memory (ECRAM) devices, we constructed a 2D semiconductor device simulation, including ions and electrochemical reactions, and used it to fit measured devices. We present the results of a device simulation model that includes Cu⁺ ions' diffusion and the charge transfer reaction between the WO_x conduction band electron and Cu⁺ (i.e., "Cu plating"). Reproducing the linear response of ECRAM devices, the effect of charging HfO_x by the Cu⁺ ions is sufficient, and WO_x is not being doped by the Cu⁺ ions. While potentiation is supported by the formation of an electron channel, an efficient depression requires the formation of high positive charge density at the channel material. At higher Cu⁺ flux, Cu⁺ reaches and penetrates the WO_x layer. While this effect enhances the potentiation response, it also initiates the "plating" reactions. Including this reaction is essential to reproducing the data of devices exhibiting sub-linear responses. We suggest that electron trapping by ions (i.e., plating) would constitute a long-term degradation process even for H⁺ based devices. [ABSTRACT FROM AUTHOR]