Off-axis electron holography and microstructure of Ba0.5Sr0.5TiO3 thin film grown on LaAlO3

TL;DR

This study investigates the microstructure and ferroelectric properties of Ba0.5Sr0.5TiO3 thin films on LaAlO3 using TEM and electron holography, revealing charge distributions related to ferroelectric polarization and defects.

Contribution

It provides detailed insights into the microstructure and charge accumulation behavior of Ba0.5Sr0.5TiO3 films at different temperatures, using advanced electron microscopy techniques.

Findings

Ferroelectric transition around 250K.

Sharp interface with misfit dislocations.

Charge accumulation varies with temperature and defect sites.

Abstract

Epitaxial Ba0.5Sr0.5TiO3 thin films grown on the (001) LaAlO3 substrates with the ferroelectric transition of about 250K have been investigated by TEM and off-axis electron holography. Cross-sectional TEM observations show that the 350nm-thick Ba0.5Sr0.5TiO3 film has a sharp interface with notable misfit dislocations. Off-axis electron holographic measurements reveal that, at low temperatures, the ferroelectric polarization results in systematic accumulations of negative charges on the interface and positive charges on the film surface, and, at room temperature, certain charges could only accumulate at the interfacial dislocations and other defective areas.