Chameleonic electrochemical metallization cells: dual-layer solid electrolyte-inducing various switching behaviours

Abstract

We present ‘unusual’ resistive switching behaviours in electrochemical metallization (ECM) cells utilizing a dual-layer (SiO_x/GeSe_x: SiO_x on GeSe_x) solid electrolyte (SE). The observed switching behaviour markedly varies with the thickness of the upper SiO_x layer and compliance current: (i) monostable switching, (ii) counter-eightwise bipolar switching, and (iii) combination of monostable and eightwise bipolar switching behaviours. Focusing on cases (i) and (iii), electrical and chemical analyses on these chameleonic cells were performed in an attempt to gain clues to the understanding of the observed complexity. The chemical analysis indicated the upper SiO_x layer as a chemical potential well for Cu ions—Cu ions were largely confined in the well. This non-uniform distribution of Cu across the SE perhaps hints at the mechanism for the complex behaviour; it may be a ‘zero-sum game’ between SiO_x and GeSe_x layers, in which the two layers fight over the limited number of Cu atoms/ions.