Self-assembled nanoscale capacitor cells based on ultrathin BiFeO3 films

Ultrathin multiferroic BiFeO3 (BFO) films with self-assembled surface nano-islands on La0.67Sr0.33MnO3/(100) SrTiO3 substrates are fabricated by a one-step pulsed laser deposition process using the Bi-rich BFO target. It is revealed that these surface nano-islands mainly consist of conductive Bi2O3 outgrowths, which serve as top electrodes for the nanoscale BFO capacitor cells with lateral size of 10–30 nm. The ferroelectric BFO layer underneath these Bi2O3 nanoislands prefers certain complex domain structure with vertical and antiparallel polarization components (the so-called “anti-domain structure”) and reduced domain switching fields. Moreover, these nanoscale capacitor cells exhibit the resistive switching IV behavior, offering opportunities for application in ultrahigh density non-volatile memories.