Two-stage filamentary mechanism in high-performance organic resistive switches

Abstract

Organic resistive switching (RS) memories are attractive storage technologies due to their low cost, huge scalability, and flexibility. In this study, organic isopropyl phenyl perylene diimide (iPrP-PDI)-based RS devices have been shown to have excellent bipolar switching performance of high continuous cycling with large ON/OFF ratios and long retention time with low operating voltages as well as being remarkably reproducible over two years. The switching parameters’ temporal and spatial variability was studied using 880 cycles across ten devices and found to be highly reproducible. The device follows a two-stage filamentary mechanism. Initially, the filament's composition was determined to be Al atoms, which evolved into a mix of Al atoms and oxygen vacancies. Conducting filaments were directly observed using atomic force microscopy (AFM). The organic semiconductor iPrP-PDI played a significant role in the switching mechanism through interactions between donors and acceptors inside its molecular structure. Furthermore, during SET/RESET cycles, discrete quantized conductance states were detected in I–V traces due to the development of atomic point contacts in the conducting filaments. These available multiple quantized levels have the potential for multilevel high-density data storage. Overall, iPrP-PDI has the potential to be an excellent choice for durable, high-performance, and highly dense memory devices for practical applications.