Polarization screening and induced carrier density at the interface of LaAlO$_3$ overlayer on SrTiO$_3$ (001)

TL;DR

This study uses density-functional-theory calculations to explore how lattice polarization affects the induced carrier density at LaAlO3/SrTiO3 interfaces, revealing a correlation between polarization screening and carrier charge.

Contribution

It provides new insights into the role of lattice polarization in carrier induction at oxide interfaces without defects, using first-principles calculations.

Findings

Polarization screening correlates with induced carrier charge.

Carrier density remains below 0.5 electrons per unit cell for few-layer LaAlO3.

Electrostatic screening compensates the induced charge in defect-free interfaces.

Abstract

We investigate the role of lattice polarization in determination of induced carrier density at the $n$-type interface of LaAlO$_3$ overlayer on SrTiO$_3$ (001) by carrying out density-functional-theory calculations. When no oxygen vacancy or defect is present, the magnitude of polarization screening in the LaAlO$_3$ layers is found to be correlated with the carrier charge induced at the interface. For the interfaces with a few LaAlO$_3$ layers, the induced charge carrier is compensated by the electrostatic screening and consequently its density remains far less than 0.5 electrons per unit cell.