Abstract

Thin-film vanadium dioxide undergoes a thermally induced phase transition over a small temperature interval near 67°C. The standard material exhibits a large change in its IR transmission on switching but no significant deviation from a room-temperature bronze color. However, an anomalous form of VO₂ was recently deposited¹ which shows a striking blue to red color change through the transition. The surface morphology of these films is radically different from the standard material, consisting of large grains 1-2 µm in diameter and separated by wide-grain boundaries. Considering the unusual microstructure of the films, it was expected that the scattered component of transmission would be large. The magnitude of scattered and directional components of the total transmittance at 24 and 100°C has been investigated in the 800-350-nm spectral range using an integrating sphere assembly and spectrophotometer. Results of these measurements are discussed, and the optical constants at visible wavelengths of the anomalous VO₂ are compared with those of the standard material.

© 1987 Optical Society of America