Quantum confinement in EuO heterostructures

TLDR: In this paper, the EuO band gap is shown to increase from 1.19ÕeV for bulk-like (d = 32 nm) to ≈1.4 ÔeV in the ultrathin films (dÔ= 1.1Ônm) and the observed band gap widening is a clear sign of a quantum confinement effect.

Abstract: Quantum wells are created from ultrathin single-crystalline EuO layers to study the evolution of the optical band gap down to the single nanometer regime. We find that the EuO band gap is indirect—independent of quantum well thickness—and increases from 1.19 eV for bulk-like (d = 32 nm) to ≈1.4 eV in the ultrathin films (d = 1.1 nm). The observed band-gap widening is a clear sign of a quantum confinement effect, which can be used to control and modify the band gap in EuO-based all-oxide heterostructures.