Study of phase composition dependent resistive switching performance in polycrystalline ErMnO₃

Rare-earth hexagonal manganites, h-RMnO₃ (R=Y, Er, Ho to Lu) have been widely studied for their multiferroic properties. There is also gaining interest in memristive device applications owing to their peculiar ferroelectric domain pattern and vortex lines. Polycrystalline hexagonal YMnO₃ thin films with promising resistive switching performance were reported recently [1]. In this work, we report the evidence of resistive switching behavior in polycrystalline ErMnO₃ thin films and study its dependence on phase composition. The films with 60 nm thickness were prepared on Pt/Ti/SiO₂/Si substrates by room temperature RF sputtering and subsequent annealing at 750 ºC for crystallization. Au/Ti/ErMnO₃/Pt devices were fabricated using patterned Ti/Au top electrodes by photolithography. The Au/Ti/ErMnO₃/Pt devices exhibit a bipolar resistive switching with a R_OFF/R_ON ratio larger than 10⁴ and an ultra-low resistance of only 10 Ω in the low resistance state, which can be of interest for CMOS circuitry with low power consumption [2] and RF power switches [3]. As polycrystalline ErMnO₃ films have multiple phases, we show the quantification of hexagonal and orthorhombic phases by GIXRD, SEM, Raman spectroscopy, and conductive AFM. The detailed structural evaluation combined with electrical characterization is utilized to develop an understanding of the role of the different phases in resistive switching phenomena. We found that a higher fraction of the orthorhombic phase reduces the operation voltage but leads to a shrinking of the memory window. This study provides insight to engineer the switching layer ErMnO₃ to improve the device performance.

References

[1] V. R. Rayapati et al., J. Appl. Phys. 126 (2019), doi:10.1063/1.5094748.

[2] H. Cao, et al., Appl. Phys. Lett. 120, 133502 (2022), doi: 10.1063/5.0085045.

[3] N. Wainstein, et al., Proc. IEEE. 109, 77–95 (2021), doi:10.1109/JPROC.2020.3011953.