Interface control of ferroelectricity in a SrRuO3/BaTiO3/SrRuO3 capacitor and its critical thickness

TL;DR

This study shows how oxygen pressure during growth controls interface quality in SrRuO3/BaTiO3/SrRuO3 capacitors, enabling the achievement of the theoretical ferroelectric critical thickness of 3.5 unit cells.

Contribution

It demonstrates that oxygen pressure during pulsed laser deposition controls interfacial termination, allowing realization of the ferroelectric critical thickness at its theoretical limit.

Findings

Oxygen pressure influences interface termination in heterostructures.

Atomically sharp interfaces enable reaching the ferroelectric critical thickness.

Controlled interface engineering improves ferroelectric device performance.

Abstract

The atomic-scale synthesis of artificial oxide heterostructures offers new opportunities to create novel states that do not occur in nature. The main challenge related to synthesizing these structures is obtaining atomically sharp interfaces with designed termination sequences. Here, we demonstrate that the oxygen pressure (PO2) during growth plays an important role in controlling the interfacial terminations of SrRuO3/BaTiO3/SrRuO3 (SRO/BTO/SRO) ferroelectric capacitors. The SRO/BTO/SRO heterostructures were grown by the pulsed laser deposition (PLD) method. The top SRO/BTO interface grown at high PO2 (around 150 mTorr) usually exhibited a mixture of RuO2-BaO and SrO-TiO2 terminations. By reducing PO2, we obtained atomically sharp SRO/BTO top interfaces with uniform SrO-TiO2 termination. Using capacitor devices with symmetric and uniform interfacial termination, we were able to demonstrate for the first time that the ferroelectric (FE) critical thickness can reach the theoretical limit of 3.5 unit cells (u.c.).