Nanoscale Bandgap Tuning across an Inhomogeneous Ferroelectric Interface

TL;DR

This paper demonstrates nanoscale, reversible bandgap tuning in ferroelectric interfaces using local strain controlled by visible light, combining experimental and computational methods to explore optoelectronic effects.

Contribution

It introduces a novel method for nanoscale bandgap engineering via light-controlled local strain in ferroelectric interfaces, supported by experimental and theoretical analysis.

Findings

Reversible bandgap variation of ~0.3 eV observed.

Switchable photovoltaic effects demonstrated.

Large local strain confirmed by spectroscopy and simulations.

Abstract

We report nanoscale bandgap engineering via a local strain across the inhomogeneous ferroelectric interface, which is controlled by the visible-light-excited probe voltage. Switchable photovolatic effects and the spectral response of the photocurrent were explore to illustrate the reversible bandgap variation (~0.3eV). This local-strain-engineered bandgap has been further revealed by in situ probe-voltage-assisted valence electron energy-loss spectroscopy (EELS). Phase-field simulations and first-principle calculations were also employed for illustration of the large local strain and the bandgap variation in ferroelectric perovskite oxides. This reversible bandgap tuning in complex oxides demonstrates a framework for the understanding of the opticallyrelated behaviors (photovoltaic, photoemission, and photocatalyst effects) affected by order parameters such as charge, orbital, and lattice parameters.