Fig. 4.

Mechanisms of SRMs. a Conductivity mechanism of double-layer oxide-based SRMs under positive bias and b positive bias. Reproduced from [17], Copyright 2023 American Association for the Advancement of Science. c Conductivity mechanism of SRMs based on Au/h-BN/graphene/h-BN/Ag van der Waals heterojunction. Reproduced from [41], with permission from Springer Nature. The conducting mechanisms, including interfacial barrier and ion migrant, of the proposed SRMs when d negative bias and e positive bias are added, respectively. Reproduced from [51], with permission of Springer Nature. f Illustration of the charge trapping and detrapping processes in the SRM cell based on Pt/NbO_x/TiO_y/NbO_x/TiN structure. Reprinted from [43], Copyright 2016 American Chemical Society