Modulation of the resistive switching of BiFO₃ thin films through electrical stressing

Abstract

The resistive switching (RS) of Au/BiFeO 3 /SrRuO 3 samples was shown to be controllable by using a thermal treatment and an electrical stressing method. Such a modulation of resistive switching effect can be associated to the oxygen vacancy movement and redistribution within the BiFeO 3 thin film and the trapping/detrapping of charge carriers at the interfaces. After the application of a negative voltage to the thin film for a stressing period, a resistive switching reversal effect occurred and the current retention ability in the low resistance state increased, indicating an increase in the trap density at the interface and an enhancement of the charge carrier trapping ability. The trap density, trap level, and Schottky barrier height all display corresponding trends in their values as a result of the modulation of RS effect. The results indicate that the greater the accumulation of oxygen vacancies at any the film/electrode interface, when a reverse bias is applied the higher the resistance ratio was under reverse bias. Its diffusion process was likely to be hindered and the trapped charge carriers could be retained after a long time of electrical stressing.

Wake-up effect in Hf0.4Zr0.6O2 ferroelectric thin-film capacitors under a cycling electric field

“…Lomenzo et al [26,27] suggested that the decreased dielectric constant in the wake-up state was caused by the tetragonal-to-ferroelectric orthorhombic phase transition. Pintilie et al proposed that the C-V curve of a ferroelectric material can be expressed by [17,28]…”

“…Because the V Ö with positive charges can attract electrons, they usually act as electron-trapping centers. [17] Initially, the V Ö accumulated at the TiN/HZO interface (Fig. 5(a)), where a large number of electrons were needed to fill traps, causing a small density of free charge in the space-charge region.…”

“…[15,16] Under an electric field, a redistribution of oxygen vacancies (V Ö) within the oxide can occur, which de-pins the domain walls and increases the remnant polarization. [13,17] A phase transition from the tetragonal to the ferroelectric orthorhombic phase is another factor in the wake-up effect, and can be stabilized by redistributed oxygen vacancies. [12,18] Starschich et al reported that the duration of the electric field was essential for the wake-up, indicating the importance of oxygen vacancy movement driven by the field.…”

Memristive Behavior of Mixed Oxide Nanocrystal Assemblies

“…The increased presence of oxygen vacancies create localized intraband gap defect states (e.g., F-centers and F 0 -centers) that significantly alter the p–d charge transfer transitions and subsequently reduce the band gap . The increased vacancy concentration manifests as both lower SET (threshold) voltage and improved switching uniformity for nanocrystal assemblies, similar to recent studies of LaAlO 3 , LaMnO 3 , and BiFeO 3 …”

“…50 The increased vacancy concentration manifests as both lower SET (threshold) voltage and improved switching uniformity for nanocrystal assemblies, similar to recent studies of LaAlO 3 , 51 LaMnO 3 , 52 and BiFeO 3 . 53 Trap-Mediated Space-Charge-Limited Current. The current−voltage responses of the 10 BZO-SZO combinations (Figure 2b,c, Figure S4, and Figure S6) were plotted on a log− log scale and fitted to determine the governing switching mechanism(s).…”