Polarization retention in ultra-thin barium titanate films on Ge(001)

Abstract

We investigate polarization retention in 10 to 19 nm thick ferroelectric BaTiO3 (BTO) grown on Ge(001) by molecular beam epitaxy. The out-of-plane direction and reversibility of electric polarization were confirmed using piezoresponse force microscopy. After reverse-poling selected regions of the BTO films to a value P with a biased atomic-force microscope tip, we monitored relaxation of their net polarization for as long as several weeks using optical second-harmonic generation microscopy. All films retained reversed polarization throughout the observation period. 10 nm-thick BTO films relaxed monotonically to a saturation value of 0.9 P after 27 days and 19 nm films to 0.75 P after 24 h. Polarization dynamics are discussed in the context of a 1D polarization relaxation/kinetics model.

Oxide‐Based Optoelectronics

“…Ponath et al investigated polarization retention in 10–19 nm‐thick ferroelectric BTO grown on Ge (001) by MBE. [ 39,40 ] The out‐of‐plane direction and reversibility of the electric polarization were confirmed using PFM. After reverse‐poling selected regions of the BTO films to a value P with a biased atomic force microscope (AFM) tip, relaxation of their net polarization was monitored for as long as several weeks using optical SHG microscopy.…”

“…[38] Copyright 2018, American Institute of Physics. [40] Copyright 2018, American Institute of Physics.…”

“…The scale bar is 10 nm. Reproduced with permission [40]. Copyright 2018, American Institute of Physics.…”