Optical properties of VO$_2$ films at the phase transition: influence of substrate and electronic correlations

TL;DR

This study investigates how substrates and electronic correlations influence the optical properties of VO$_2$ thin films during the phase transition, combining experimental reflection data with theoretical band structure calculations.

Contribution

It provides a detailed analysis of substrate effects and electronic correlations on VO$_2$'s optical properties across the phase transition, with new insights into interband transitions and charge carrier parameters.

Findings

Substrate type affects optical response during phase transition.

Electronic correlations significantly influence the phase transition behavior.

Identified specific interband transitions associated with VO$_2$ phases.

Abstract

Thin films of VO$_2$ on different substrates, Al$_2$O$_3$ and SiO$_2$/Si, have been prepared and characterized from room temperature up to 360 K. From the band structure in the rutile metallic phase and in the monoclinic insulating phase the optical properties are calculated and compared with reflection measurements as a function of temperatures. Various interband transitions can be assigned and compared with previous speculations. We extract the parameters of the metallic charge carriers that evolve upon crossing the insulator-to-metal phase transition and find effects by the substrate. The effect of electronic correlations becomes obvious at the phase transition.