Abstract
Switchable diode effect in ferroelectric diodes has attracted much attention for its potential applications in novel nonvolatile memories. We briefly review recent investigations on the switchable diode effect in ferroelectric diodes both experimentally and theoretically. Many recent studies demonstrate that the interfacial barrier between the metal-ferroelectrics could be modulated by the polarization charges, and the ferroelectric polarization that can be reversed by an external electric field plays a dominant role in the switchable diode effect. Moreover, we review a self-consistent numerical model, which can well describe the switchable diode effect in ferroelectric diodes. Based on this model, it can be predicted that it is a better choice to select metals with a smaller permittivity, such as noble metals, to obtain a more pronounced switchable diode effect in ferroelectric diodes.
Highlights
Ferroelectric materials are of characteristics to maintain the polarization state in the absence of a voltage and the possibility to reverse the polarization direction by applying an electric field [1,2]
It is an obvious idea to design robust nonvolatile random access memories based on intrinsic switchable ferroelectric polarization in the ferroelectric materials
The polarization charges can affect the barrier at the interface between electrodes and ferroelectrics, and the reversal of the polarization produces a change in the band diagram [7,8]
Summary
Ferroelectric materials are of characteristics to maintain the polarization state in the absence of a voltage and the possibility to reverse the polarization direction by applying an electric field [1,2]. The switchable diode effect means that the polarity of the diode can be reproducibly switched by the reversion of the applied electric field in the MFM structures, due to the polarization modulated barrier. The switchable diode effect was observed for the 120 nm film, where the applied voltage range is smaller than that for the 240 nm film (about ±3 V). To further confirm the observed switchable diode effect, Wang et al used electrical pulses of ±8 V for 200 ms to induce the reversion of the polarization in the 240 nm BFO film, and measured I-V curves with a sweep voltage of ±2 V as shown in Fig. 2 [27,30]. It is worth mentioning that an excellent retention was obtained in this structure ascribed to Current (μA) Current (μA)
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