Optical properties of monoclinic HfO2 studied by first-principles local density approximation +U approach

TL;DR

This study uses a first-principles LDA+U approach to investigate the optical properties and band structure of monoclinic HfO2, successfully reproducing experimental band gaps and revealing unique features related to its crystal structure.

Contribution

It introduces an LDA+U method to accurately model the electronic and optical properties of monoclinic HfO2, highlighting structural effects on its optical features.

Findings

Reproduces experimental band gap of monoclinic HfO2

Identifies a shoulder in the dielectric function at the band edge

Predicts similar optical features in monoclinic ZrO2

Abstract

The band structures and optical properties of monoclinic HfO2 are investigated by the local density approximation (LDA)+U approach. With the on-site Coulomb interaction being introduced to 5d orbitals of Hf atom and 2p orbitals of O atom, the experimental band gap is reproduced. The imaginary part of the complex dielectric function shows a small shoulder at the edge of the band gap, coinciding with the experiments. This intrinsic property of crystallized monoclinic HfO2, which is absent in both the tetragonal phase and cubic phase, can be understood as a consequence of the reconstruction of the electronic states near the band edge following the adjustment of the crystal structure. The existence of a similar shoulder-like-structure in the monoclinic phase of ZrO2 is predicted.