Tunnel current model of asymmetric MIM structure levying various image forces to analyze the characteristics of filamentary memristor

Abstract

Electro-formation in metal insulator metal (MIM) structure causes the emergence of the conductive filament and also leaves a tiny insulating gap amid upper electrode and conductive filament. Since the material property of conductive filament is unlike that of the upper electrode, it is vital to consider these dissimilarities of electrodes in tunneling phenomena. In this paper, the trapezoidal potential barrier of an insulating film sandwiched between two dissimilar electrodes (asymmetric MIM) is accounted for and superimposed with triangular, parabolic and rectangular image force potentials, to derive the corresponding mean barrier heights. Then, the impact of the insulating film thickness, metal’s work function difference, and the dielectric constant of the insulating film on tunneling current density are investigated, employing the same mean barrier potential. Finally, the obtained results are implemented in conductive filament-based memristor model to analyze its physical behavior through pinched hysteresis I–V characteristics. It is ascertained that symmetric results are obtained in forward and reverse biased conditions. The incorporation of triangular image potential suppresses the barrier foremost, whereas parabolic image potential (PIP) has moderate effects on barrier lowering and rectangular image potential exhibits least lowering of the potential barrier, which renders minimum current. The switching dynamics of memristor apprises that PIP manifests only 0.5% deviation with experimental results in OFF switching and also shows good agreement in ON switching. The design is endorsed by comparing the outcomes with experimental and simulated data. This model enables reconfigurable and neuromorphic computing applications of the memristor.