Fabricating Stoichiometric Vanadium Dioxide Thin Films for Modulating Light Emission

The near-room-temperature insulator-to-metal phase transition in vanadium dioxide (VO$_{2})$ can produce drastic changes in resistivity and optical constants. In the nanophotonics field, this property of VO$_{2}$ is particularly attractive, because it can be used to manipulate the local environment of light emitters. However, since vanadium exhibits a large number of stable oxides, it can be challenging to obtain stoichiometric VO$_{2}$. Although the published literature contains many reports of optimal fabrication conditions, such parameters can vary substantially from system to system due to differences in architecture. Here, we will present an experimental procedure for optimizing stoichiometric VO$_{2}$ thin film growth by sputtering. Temperature-dependent spectroscopic ellipsometry, x-ray-diffraction, and resistivity measurements have been used to characterize sputtered VO$_{2}$ thin films. The time-domain switching behavior of VO$_{2}$ has also been also investigated by pump-probe spectroscopy. Finally, building on the work of Cueff et al., we will show how these VO$_{2}$ thin films can be electrically switched to modulate light emission by erbium ions faster than their excited state lifetime.