Theory of unidirectional bulk conduction under trap density gradient for resistance switching

Nonlinear bulk conduction under graded distribution of traps is shown to exhibit well-defined rectification without relying surface barriers [1,2]. This solves a puzzle in the resistance switching that frequently exhibits both unidirectionality (rectification) and bulk-limited conduction characteristics. In addition, it also resolves an old puzzle of nonideal rectifying characteristic showing bulk properties. This paper briefly introduces the theory [1,2] and indicates that a fraction of reported resistance switching phenomena is due to the change of trap distribution. The theory can also be used to identify the ferroelectricity effect on the resistance switching. In addition, the phenomena treated here can be important, because carriers are injected during the polarization switching.