Ferroelectric Switching in Hybrid Molecular Beam Epitaxy-Grown BaTiO3 Films

TL;DR

This study demonstrates the direct measurement of remnant polarization in MBE-grown BaTiO3 films, revealing ferroelectric switching behavior and structural defect influences in epitaxial heterostructures.

Contribution

First in-situ growth and direct polarization measurement of MBE-grown BaTiO3 films with detailed ferroelectric characterization.

Findings

Remnant polarization P_r = 15 μC/cm² measured in MBE-grown BaTiO3.

Hysteretic P-E curves observed at frequencies 500 Hz to 20 kHz.

Structural defects may cause asymmetry in switching and leakage.

Abstract

Molecular beam epitaxy (MBE) is a promising synthesis technique for both heterostructure growth and epitaxial integration of ferroelectric BaTiO3. However, a direct measurement of the remnant polarization (P_r) has not been previously reported in MBE-grown BaTiO3 films. We report the in-situ growth of an all-epitaxial SrRuO3/BaTiO3/SrRuO3 heterostructure on Nb-doped SrTiO3 (001) substrates by hybrid MBE using metal-organic precursors. This capacitor structure consisting of 16 nm SrRuO3/40 nm BaTiO3/16 nm SrRuO3 shows hysteretic polarization-electric field (P-E) curves with P_r = 15 {\mu}C cm-2 at frequencies ranging from 500 Hz to 20 kHz, after isolating the intrinsic ferroelectric response from non-ferroelectric contributions using the Positive-Up-Negative-Down (PUND) method. We hypothesize that the asymmetry in switching behavior and current leakage has origins in structural defects.