Optical properties of VO2 films at the phase transition: Influence of substrate and electronic correlations

Abstract

Thin films of VO2 on different substrates, Al2O3 and SiO2/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.

Basic aspects of the metal–insulator transition in vanadium dioxide VO2: a critical review

“…With this double process M 1 becomes an insulator (semi-conductor) if δE is large enough so that the bottom energy of the π * band is higher than the upper energy of the d B // band, as shown in Figure 12b. δE measured at ≈ + 0.68 eV at ambient pressure [107,108] supports this scenario. Note that in the opposite situation of negative δE, M 1 should remain metallic.…”

Modulated scattering technique in the terahertz domain enabled by current actuated vanadium dioxide switches

“…Typical broadband bowtie antennas have input impedances with a constant real part (typically of the order of tens of ohms depending on both substrate and geometry) and a small imaginary part over the frequency band of interest. On the other hand, the VO 2 switch impedance is dominated by carrier dynamics in VO 2 , which is approximately the same as in DC transport since the collision frequency is of the order of tens of terahertz 27 28 29 , as confirmed by direct measurements of the THz conductivity showing negligible imaginary part and a real part with low dependence on frequency 30 . Hence, the VO 2 switch can be considered as resistive, i.e.…”

Self-regulated transport in photonic crystals with phase-changing defects

“…The constants 0 and ∆ D have been extracted from various experimental data presented in the literature in a way that matches the observed values of D in the dielectric and metallic phase [4,14,[27][28][29]. We have found that 0 can take values between 0.02 (or even lower) to 0.1 while the extracted ∆ D varies between 25 − 80.…”