Novel synthesis and design methods of optical thin film structures using vanadium dioxide phase change material

Abstract

Recent developments in phase change materials have led to a new generation of electronic and photonic memory devices and thermally tunable devices. Vanadium dioxide (VO2) and Germanium Antimoy Telluride (GST) are two of the most developed phase change materials. The focus of this work is on vanadium dioxide. Current methods of growing vanadium dioxide rely on reactive physical vapor deposition on heated and lattice-matched substrates. This is often a difficult deposition process with a very narrow process window. The high process tem- peratures, patterning and etching challenges, and the lattice-matching requirement severely limit the number of materials VO2 can co-exist with. As a result, compared to other types of inorganic optical thin film materials, the development of practical devices exploiting VO2 has been modest. In this paper, novel and simplified approaches to producing VO2 thin films is discussed, especially in regards to creating multilayer optical structures, tunable optical filters, switchable wiregrid polarizers, and tunable Bragg reflectors. The growth and characterization of nanostructured VO2 films are also discussed.