低驱动场钙钛矿铁电超薄薄膜设计及其多态隧穿特性

The ferroelectric tunneling junction, with a metal-ferroelectric ultra-thin film-metal structure, has different tunneling resistance states through polarization manipulation, leading to potential applications in next-generation information storage devices with low-power consumption, fast reading/ writing speed, high storage density, and non-volatility. However, the ferroelectric thin films still experience high-temperature rises with reduced stability due to high driving fields, and reducing the driving electric field is crucial for designing ferroelectric tunneling devices. The ferroelectric thin films with coexisting domains have lowered barriers and decreased driving electric fields for domain switching, which are achieved through substrate manipulation. Herein the substrate effects on the driving field, the tunneling resistance switching ratio and the tunneling properties, were studied based on the WKB approximation combined with the Landau phenomenological theory. The results show that, the ferroelectric tunnel junction with coexisting domains exhibits 3 resistive states corresponding to out-of-plane and in-plane polarizations. The effective driving electric field can be reduced to 25 MV/ m, which is 76% lower than that with 2 resistive single domains. The proposed theoretical framework provides a fundamental understanding of the formation of multi-state and reduction of the driving field for low-energy, multi-resistance ferroelectric storage devices.