Polarization Controlled Ohmic to Schottky Transition at a Metal/Doped Ferroelectric Interface

TL;DR

This study demonstrates how switchable ferroelectric polarization in electron-doped BaTiO3 can reversibly alter the interface from Ohmic to Schottky, causing a significant change in resistance suitable for device applications.

Contribution

It introduces a first-principles and electrostatic modeling approach to show polarization-controlled electronic transition at a ferroelectric/metal interface.

Findings

Switchable polarization controls charge accumulation at the interface.

The interface transitions from Schottky to Ohmic contact upon polarization reversal.

Resistance changes by five orders of magnitude with polarization switching.

Abstract

Ferroelectric polar displacements have recently been observed in conducting electron-doped BaTiO3. The co-existence of a ferroelectric phase and conductivity opens the door to new functionalities which may provide a unique route for novel device applications. Using first-principles methods and electrostatic modeling we explore the effect that the switchable polarization of electron-doped BaTiO3 (n-BaTiO3) has on the electronic properties of the SrRuO3/n-BaTiO3 (001) interface. Ferroelectric polarization controls the accumulation or depletion of electron charge at the interface, and the associated bending of the n-BTO conduction band determines the transport regime across the interface. The interface exhibits a Schottky tunnel barrier for one polarization orientation, whereas an Ohmic contact is present for the opposite polarization orientation, leading to a large change in interface resistance associated with polarization reversal. Calculations reveal a large (five orders of magnitude) change in the interface resistance as a result of polarization switching.