Stable reconfiguring, high-density memory and synaptic characteristics in Sn alloyed CsPbI3 perovskite based resistive switching device

Abstract

In search of efficient data storage devices, the need of the hour demands novel materials that can offer superior speed, low power consumption and reproducibility. Here, we have chosen a halide perovskite material for the development of reconfigurable memory properties. A metal-insulator-metal structure comprising of Au/α-CsPbI3/ITO has been fabricated to realize non-volatile memory characteristics. However, the active cubic phase of CsPbI3 is not stable at room temperature if not shielded properly as found in literature. To minimize the effect of passivation and interface reaction, the CsPbI3 was alloyed with Sn at the Pb-site. The substitution resulted in stable phase of α-CsPbI3 at room temperature due to increase in tolerance factor. Thus, the device with 10 % Sn alloyed perovskite shows reliable and uniform resistive switching behavior with high ON/OFF ratio (>104), low operating voltage (<0.5 V) along with multi-bit operation capability. On the hand, the device with orthorhombic structure, i.e. δ-CsPbI3 failed to demonstrate any significant switching behavior with the similar operating voltages. Such discrepancy in device mechanism could be attributed to the structural dissimilarity between the two phases, where migration of ions/vacancies holds prime role. Finally, the change in device resistance was postulated by valance change mechanism (VCM), which was validated by conducting atomic force microscopy (c-AFM). This switching mechanism and low OFF state current of the device were utilized to emulate synaptic characteristics in the device consuming very low energy and pave the way for the development of next-generation multi-functional electronic devices.